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Hello, quick question that probably requires a not so quick answer.  I have a '55 Super and the transmission has met its maker.  I found a dynaflow out of a '58 locally but I'm  not 100% sure it will be a straight swap.  Any info would be appreciated.  My transmission shop thinks it probably will fit one way or another but I'd like to know more going in.

 

Thanks!

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 Only 55 Roadmaster and Super use the same transmission. Hollander #478.  No other year or model is a direct fit. They also say 53 Roadmaster and Super  Dynaflow #369 can be installed by adapting rear support. They don't show further interchange for a complete transmission. They don't say how much work it is to adapt the rear support. Maybe this will help.

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On 8/21/2020 at 6:45 AM, Psevins said:

Hello, quick question that probably requires a not so quick answer.  I have a '55 Super and the transmission has met its maker.  I found a dynaflow out of a '58 locally but I'm  not 100% sure it will be a straight swap.  Any info would be appreciated.  My transmission shop thinks it probably will fit one way or another but I'd like to know more going in.

 

Thanks!

Working with dynaflows with closed driveshaft can be challenging when folks only know parts of the answer! Farther into the Hollander reading you would find them recommending a 1956 Buick Dynaflow as "far superior" to your existing 1955. It is an exact fit in your car as far as length. The ujoint on the 55 trans has coarse splines as compared to 56 with fine splines. These are held on with one bolt and interchangable. 1957 has a longer rear housing and a bell housing bolt pattern fitting  57-66 Buick engines, but not 322's or 264" engines that ended production with the 1956 322". One reason 56 dyna is better is the extra stator in the torque convertor. All things being equal a 1956 Buick with dyna will have better acceleration than 55 even when considering 255hp in 56 & 236hp tops for 55. So, IMHO, if you hafta do a trans and U wanna use the KISS(keep it simple senior) find a rebuilt 56 that being sold or get a 56 core trans rebuilt. Good luck with your project! Hope this helps!

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I looked this up in a 66 Hollander. It says the 56 trans with it's Ujoint fits 55 Special and Century only. But I have found that different year Hollander interchanges vary  and are often expanded or limited from issue to issue.

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On 8/25/2020 at 9:33 PM, misterc9 said:

I looked this up in a 66 Hollander. It says the 56 trans with it's Ujoint fits 55 Special and Century only. But I have found that different year Hollander interchanges vary  and are often expanded or limited from issue to issue.

None of the print material can be relied upon solely! In this particular case, I own a 1955 Century and installed a 56 trans in it, so Im speaking from personal experience, not just from readings Ive done, which happened as well, as I researched b4 attempting the swap. Thanx for the caveat! We all need to make sure to use the most verified advice!

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2 minutes ago, 2carb40 said:

None of the print material can be relied upon solely! In this particular case, I own a 1955 Century and installed a 56 trans in it, so Im speaking from personal experience, not just from readings Ive done, which happened as well, as I researched b4 attempting the swap. Thanx for the caveat! We all need to make sure to use the most verified advice!

As stated, 56 trans can NOT be used in 55 without swapping ujoints! All 55s use a coarse spline on the driveshaft end, fine spline 56-all.

On 8/24/2020 at 9:23 PM, misterc9 said:

 Only 55 Roadmaster and Super use the same transmission. Hollander #478.  No other year or model is a direct fit. They also say 53 Roadmaster and Super  Dynaflow #369 can be installed by adapting rear support. They don't show further interchange for a complete transmission. They don't say how much work it is to adapt the rear support. Maybe this will help.

 

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Which means he would have a fairly easy time putting a 1956 transmission in as it is the same length as his existing dynaflow. Thanx for clarifying which model he has. I just hope he didnt get confused when Hollander was incorrectly quoted saying the 56 trans only fits Spec and Cent. It doesnt! I had to engineer useing a modified ujoint to make it work! Did I mention I did this? In closing; 55 SUPER&ROADMASTER TRANSMISSIONS ARE THE SAME LENGTH AS ALL 56 DYNAFLOWS! Thanx for your attention! 

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14 hours ago, misterc9 said:

Mr Psevins the original poster has a 55 Buick Super.

 

He also says he found a 58 transmission.

But alas, he has never returned.

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