46-48 Chrysler differential question.

I'm having a discussion with a 48 Chrysler Windsor owner who says his car has the higher speed 3.54 rear end ratio. My 1948 DeSoto has a 3.73 rear end. I don't doubt that he has a 3.54 rear end, but it is my guess that the standard rear end on 46-48 DeSotos and Chrysler Sixes with semi-auto trans. was 3.73. My DeSoto shop manual and Parts manual list the DeSoto as having the 3.73 rear end as standard and the 3.54 read end as special. I know that the 41 - 42 Chrysler Sixes and DeSotos had 3.54 rear ends as standard, but I think it changed in 1946 to 3.73. My friend offered as proof a spec from a 1946 Chrysler Data Book showing the rear end as only 3.54. Can you check your 1948 Parts Manual and Shop Manual to see what it says about rear end differential ratios for the Chrysler sixes with M-5 transmissions? It can be found in the section on Rear Axles. Thanks, Marc.

My manual shows 3.54 for C38 with hydraulically operated transmission and 3.9 for standard transmission.

^^^^^^The info shown above by jcmiller is 100% correct.

I think most all 1946-48 Chrysler Windsors use the 3.54 ratio as I have seen in person over all the years I've been restoring rebuilding them.

Always the 3.54 ratio is what I've taken out of them on a restoration job.

1953 Canadian Service Data Book says 1946 - 48 Chrysler six, 39:11, straight eight models, 37:11. Being the number of teeth on the crown gear and pinion.

So are you saying that the 46-48 Chrysler six had a different standard rear end than the DeSoto which had a 3.73 ratio? If so, why the difference? Both DeSoto and Chrysler had 3.54 ratios in 41-42. Although, my DeSoto Parts Book does mention the 3.54 ratio as being special equipment. Why would they have different rear ends in 46-48? The only difference in the Chrysler six and the DeSoto is a slighter bigger engine, 250 c.i vs. 236 c.i.

And what have you taken out of 46-48 DeSotos, if you have worked on them?

I took a 3.54 out of a 42 S10 DeSoto convert several years back to rplace the housing gasket and pinion seal.

It's too bad your DeSoto car has the very common 3.73 ratio rear end.

The 11 bolt six cylinder 3.54 ratio's rear ends are highly sought after for the 1941-52 Plymouths.

The 1949-50 eight cylinder Chrysler NewYorker/Saratoga's s also use a 3.54 ratio rear end but it's a bigger and heavier duty 10 bolt housing/gear set.

Why is it bad to have a 3.73 rear end? And did only DeSotos have them? What ratio did Dodge have with fluid drive?

The low geared rear end is better for acceleration and traffic driving but the engine has to go very fast on the highway. The higher gear (lower numerical) is better for today's highways.

Modern cars have much higher gears than the oldies, we are not used to the engine roaring at 60MPH.

I remember I used to drive a 1950 Chrysler in the early 80s and had no problem with freeway speeds. Then I got a 1950 Plymouth businese coupe with a 3-speed manual and at 55 mph it was screaming for a 4th gear! I remember driving my DeSoto on the freeway, but I don't remember it having a problem with freeway speeds, but that memory is 30 plus years ago. Is the driving difference between a 3.54 and a 3.73 really noticeable?