Big three or four body panel interchange

[Guest prs519]

Not sure if this should be a seed for the tech forum, or for the

General discussion. Of curiosity, I would like to know when the

"majors" started to share body panels, and other parts, across

"state lines", so to speak. For example, it seems doubtful that

a 1922 Oldsmobile door would be likely to fit a 1924 Cadillac. But later

on, one might find such an interchange possible say...something from

a 1948 Buick interchanging with a 1949 Cadillac. My Hollanders reprint

only goes to 1928, and that sparsely, so, do any of you know when

this started to commonly happen with so many of the parts the same

in the different divisions (of course, except the part number?) Regarding this

last, were the makers trying to fool the rank and file buyer into thinking

his car was made out of parts peculiar only to its unique species, by assigning

each its own part number, even though it clearly may have been made by the same forging or machining tools and operations, etc.?

[Rusty_OToole]

This goes way back. In 1929 Walter Chrysler created the DeSoto by putting a six cylinder engine in the Plymouth. Body chassis etc were the same, with more luxurious trim.

Around 1916 Billy Durant created a new car by taking a Buick body, cutting it in 4 pieces and moving them apart. Then they welded in strips of metal and there was their prototype.

Ford and Cadillac used the same body in 1903. Ford had a 2 cylinder engine, the Cadillac 1 cylinder. You could tell them apart by the shape of the radiator.

If you want to talk custom bodies, a company like Murphy or Derham would fit the same body to any chassis the customer preferred. They kept the more popular bodies in stock, these were known as "bodies in white".

When exactly they started to rationalize in this way I don't know. But would say it dated back to the earliest days of the industry in one way or another, but became common practice in the twenties. When all steel bodies came in, it really paid to do this because the high cost of tooling could be spread over a larger number of bodies. When they were made of metal panels over a wood frame the cost of making a different body was much less.

[joe_padavano]

The reference guide for parts interchangeability is the Hollander Interchange Manual. They're on the 76th edition this year, but this one covers the 1920s through 1948:

https://hollanderinterchange.net/catalog/product_info.php?cPath=21&products_id=28&osCsid=df629e50e6001d3931a4e92f4151a225

[Restorer32]

A 1947 Cadillac Sedan Body is identical to a 1948 Buick Body as are the convertible bodies and top assemblies and I believe the large body Olds. I believe Cad and Buick shared some body parts as far back as 1935 at least when used on Convertible Sedans.

[Rusty_OToole]

By the thirties GM had worked out a system where they used just 3 basic body shells to cover all their cars. They were called A, B, and C bodies.

A body was for all Chev and Pontiac cars, and the base model Olds 66. B body for the larger Oldsmobile 88, Buick Special and Century and some LaSalle and small Cadillac. C body for most Cadillacs, Buick's Roadmaster, and certain years of Olds 98.

Oldsmobile's model numbering system had 2 digits, the first being body size,6 7 8 or 9 for A B or C body. The second number for cylinders, 6 or 8. Models ranged from 66 to 98.

The rule wasn't always rigidly observed. The Olds 88 of the early 50s used the Chev A body and so did the earlier 66 model from the forties. So they weren't too particular in identifying body size in their names.

Each body would be used for 2 or 3 years with facelifts in the in between years. They might bring out a new A body one year, a new B body the next and a C body the third.

For example in 1948 Cadillac got a new C body and so did the Futuramic Olds 98. But Buick stuck with the old C body for one more year because the head of the Buick division didn't like the new body.

In 49 they brought out a new A body and B body. About this time Olds gave up the C body and made only A and B body cars. So it can get confusing.

1959 is a unique year. They decided to go even farther and make all GM cars off one body except for Corvette. Chev, Pontiac, Olds Buick and Cadillac all started from the same body shell, suitably modified. This was to allow them to have a new body every 2 years by getting the maximum use out of one body.

The reason this was a 1959 only deal is that in 1960 they brought out the Corvair. So now they were back to 2 steel bodies plus Corvette.

Next year they came out with the Pontiac Tempest, Olds F85 and Buick Special that used a heavily modified Corvair body shell.

By 64 they had a Corvette body, a Corvair body, a Nova body,a Chevelle body, a BOP compact body in 3 flavors (Tempest F85 and Special) plus the full size bodies. Whether they were still using the same shell, suitably modified, for all full size cars I'm not sure.

One way to tell if 2 cars are made from the same basic body shell is to look at the windshields. If the windshields are identical they are brothers under the skin. The windshield and cowl area is the one part least likely to change because it is so complicated and expensive to design and build.

Edited September 27, 2010 by Rusty_OToole (see edit history)

[Rusty_OToole]

Here's another one that floored me. A friend had a 59 Chrysler New Yorker that needed a new roof. He looked around and found a junked 57 Plymouth. The roofs were identical. You could cut the Plymouth roof off at the door posts, weld it on the Chrysler and no one would be the wiser.

So they used the same body for Plymouth Dodge DeSoto and Chrysler. Only Imperial had a unique body.

If you look at pictures of the 57 Plymouth Dodge DeSoto and Chrysler you can see where the front part of the body and even front fenders are basically the same, only the grille is different. Around back all have different rear fenders and tail fin styling.

[Restorer32]

Which explains why a '59 Cadillac Convertible front door window frame is identical to a '59 Chev Conv windshield frame. Strange but true, call Ripley.

[poci1957]

Rusty's outline is excellent, and on a very interesting topic.

A key element to this question is the understanding that from the beginning body design and chassis construction were treated as two separate functions. The auto company was there to produce car chassis, and bodies were purchased from outside coachbuilders (who more or less evolved from carriage making). This is why a 1903 Ford and Cadillac might share bodies, because they both came from the same outside supplier subcontractor.

The most sophisticated practicioner of the art of body sharing was Fisher Body, who started out as an independent coachbuilder and was purchased by GM to provide their bodies in-house. But even as a GM division Fisher was fiercely independent and made it a point to put their name on each "Body by Fisher" all the way until they were decommisioned in the 1980s.

Reportedly, early in the Depression someone at GM noticed that even though each division ordered their own bodies their measurements were within fractions of an inch of each other. A lightbulb went off that if these bodies were a similar size and configuration why not standardize and save the money and differentiate them by trim and other visual cues. This would save GM billions over the years, and was carried out especially well since Harley Earl was designing the cars and was very careful to make them distinctive enough that they did not result in lookalike cars (at least not in his day). I believe the first "A" body shared by Chevy and Pontiac came for 1933 and soon the A, B, C (and sometimes D) body sharing as Rusty explained was in force for the next 25 years.

Some might say that this was to "fool" the buyer, but GM never denied the body sharing. As Rusty says, people could figure it all out if they checked on the windshields and door parts interchanges. The divisions were somewhat independent and they were proud to maintain their individuality and differ as much as possible. The system was brilliantly handled--GM made money, the customer got value, and they loved the cars. Todd

[WQ59B]

^ But one needs to be careful in generalizing here, IMO.

Greenhouses often interchanged (glass, roof skin), but the body shells were primarily different.

>>"1959 is a unique year. They decided to go even farther and make all GM cars off one body except for Corvette. Chev, Pontiac, Olds Buick and Cadillac all started from the same body shell, suitably modified. This was to allow them to have a new body every 2 years by getting the maximum use out of one body."<<

In '59, pushed by the crash mid-stride styling redesign, the shells had more in common than previously... but in actuality (the usual greenhouse sharing aside) the '59 shells shared firewalls, front floor pans & front inner door structures. This still leaves the entire front clips, the rear floors & doors, and the entire rear clips as unique. And you still got some variances in the 'shared' surfaces- like the roof section of the '58 Impala, and the olds/Buick 3-piece rear windows on the '57s.

[keiser31]

A lot of years saw Chrysler Corporation put Plymouth front clips on Dodges in Canada. I have seen many interchanging body parts within Chrysler Corp.

[Guest Jim_Edwards]

The reference guide for parts interchangeability is the Hollander Interchange Manual. They're on the 76th edition this year, but this one covers the 1920s through 1948:

https://hollanderinterchange.net/catalog/product_info.php?cPath=21&products_id=28&osCsid=df629e50e6001d3931a4e92f4151a225

Hollander's will only give exact interchange. For Example: Though two doors might be exactly the same on two different brands or even within a brand if there is a difference in the trim mounting they are not considered direct interchange in the Hollander's books. A really good example of this is with the 1955-1956 Cadillac Eldorados and the everyday garden variety Cadillac Series 62 hoods. The hoods are exactly the same with exception of hood ornament mounting. Not a problem if one needs one and doesn't mind filling unneeded holes and drilling others. However, Hollander's does not consider the two hoods as being direct interchange, because they are not in all respects.

Jim

[Guest South_paw]

Jim,

The 1955 Eldorado hoods were the same as the standard Cadillac hood but the 1956 Eldorado hood was not. The standard Cadillac hood has a stamped mounting base for the flying Goddess whereas the Eldorado hood does not have this stamping. Will the hood fit? Sure will, but it will take a lot more than just filling a few holes to convert it See pics

Here's a standard 56 hood,

Here's a 1956 Eldorado hood,

[Guest Jim_Edwards]

Lou, having a '56 Eldo I should have known that was a bad comparison thanks for making the correction before someone went out and bought a common Caddy hood to replace their messed up Eldo hood.

I'm darn handy with metal working tools and welders but I don't think I would want to tackle making a conversion from a standard '56 hood to a '56 Eldo hood.

Jim

[Rusty_OToole]

We have had some discussion of other makes but Ford seems to be left out.

In the thirties Ford got a new body every 2 years with a face lift, including new grille on years in between. They had a peculiar system from 1937 to 1939 by which the Standard Ford got the previous year's Deluxe grille.

Lincoln Zephyr debuted in 1936 and went on all by itself until 1948. After the war it was the sole Lincoln offering as the seniors had been dropped.

Mercury was added to the line in 1939 and it got its own body, but only for 2 years. Starting in 1941 it got the Ford body on a longer wheelbase frame with different trim and frontal styling.

The senior Lincoln was its own design and did not share a body. I believe all their bodies were of the traditional wood frame with metal panels construction and many were custom made.

Postwar Ford, Mercury and Lincoln continued their prewar designs until 1949.

Then came some interesting revisions. Ford got its own body, Mercury became a junior Lincoln and shared the Lincoln body, and then there was the Lincoln Cosmopolitan with its own unique body.

The story is that the Mercury was supposed to be the Ford, the Lincoln was supposed to be the Mercury and the Cosmopolitan was supposed to be the Lincoln but it turned out they were too expensive. So they designed a new Ford and moved the others up a step in the hierarchy.

For 52 there was an all new Lincoln, and all new Ford and Mercury. These last 2 shared a body.

One thing I am not quite clear on is the 55-56 Ford body. Was it all new or a major revision of the 52-54 model? Lincoln I am pretty sure kept the same body from 1952 to 57 although it was heavily face lifted annually.

57 started a new system again. There was a basic Ford body for the lowest priced Fords, a different body for deluxe Fords, like the new Fairlane. Another body for Mercury. And the Lincoln with the last facelift of its 52 body. Add the Thunderbird and Continental and Ford has now gone from 2 bodies in 1948 to 5 1/2 in less than 10 years.

58 continued the 57 Ford and Mercury bodies but added Edsel. The Edsel had 4 models, Ranger Pacer Corsair and Citation in order of cost. Ranger and Pacer were built on the Ford body and Corsair and Citation used the Mercury.

Lincoln got an all new body this year and so did Thunderbird. The Continental was dropped, but the new 4 place Thunderbird effectively took its place.

The same continued until 1961 except for the addition of Falcon in 1960. In 61 they slashed the number of bodies considerably. There was now Falcon and Comet which shared a body. Full size Ford and Mercury shared a body and Lincoln got its all new 4 door Continental body. Plus the Thunderbird.

That's about enough for now. If anyone is interested I could continue into the sixties with the Mustang, Cougar and Fairlane additions.

[Guest Jim_Edwards]

Nice bit of Ford history, but just exactly has that to do with the practice among some automakers using some of the same body parts across all or some of their brand product lines? I've owned many, many Ford Products over the years and can say that few Post WWII body parts were shared across production lines to the point of direct interchangeability.

Virtually all automakers share basic body shells across product lines but little attached to those body shells were/are a direct interchange across their given brands and sometimes not even models within brands due to trim attachment differences.

Jim