Technical '51 buick rearend swap question

i have a 51 buick straight 8 with 3 speed manual ******. im trying to get it where i can run the car on the highway, ive read where the later model buicks with dynaflow trans have a better rearend gear ration for higher speeds. ive gotten a hold of a 55 buick parts car with the nailhead, dynaflow trans and running gear. will swapping out the rearends give me the highway performance in my 51? any help or info will be greatly appreciated

 

The '55 may have a 3.36 gear ratio, which is a reasonable highway gear. Also, the '55 center section should fit your axle housing......the bolt pattern changed in '56.

Driveshaft/torque tube length is an open question. You'll need to measure that and compare. If there is a difference in length, you should be able to use the '51 driveshaft and torque tube on the '55 center section.

Ray

 

I got the 55 apart today, doing the math from the stamping a it has a 3.2:1 gear section. not sure what that'll give me, I read on here a 3.6:1 drops about 400rpm at 60. Hoping my shaft and tube will work..I'll know in a couple days. Only place I'm having luck with getting buick parts is 'bobs automobilia' in Ca, any body know of anywhere else??