Any know if a 1947 diff. (ring and pinion for a 60 series)
will fit my 1941 Special.
will it bring the rpm. down at cruice speed ?

Michael Larsen

Hi Michael,

Yes, the rings and pinions from most Buicks up to about 1955 or so will physically fit your '41's rear end housing. The tough part is getting the pinion out of the donor car's torque tube and installed properly in your car's unit.

Your car has either a 4.1 or a 4.4 rear gear, and most large series Buicks have 3.9, 3.6 or even lower gears (Dynaflow cars tended to have the lowest gearing), so finding out what you have now will help determine whether a particular gear is worth the (big) hassle of the change. I wouldn't go from a 4.1 to a 3.9, but I would go from a 4.4 to a 3.6 or 3.42.

Hope this helps. Enjoy your car!

The simplest way to do the job is to put your drive shaft and torque tube on the later center section. they will interchange from 1940 to 1955. The axles have the same splines,and they will bolt into the 41 axle housing.

Michael,
FYI - The 1941 Buick series 60 & 70 optional rear axle ratio of 3.6 has a ring gear with 51 teeth (P/N 1320219) and a pinion with 14 teeth (P/N 1320220). The correct speedo drive gear has 18 teeth (P/N 1315064 for the assembly). The speedo gear is marked 18-T-1315022 on the gear.
Grandpa