C2_Universal Joint _drive shaft to differential

[Steve D.]

There is a generous amount of space on each end of the universal joint when it is placed in the yolk of the differential. (Picture below) Am I missing spacers or shims, or do I have the wrong joint. The joint fits perfectly in the drive shaft, and although it's been a while, I am pretty certain that I compared the joint to the one that was replaced before installing the new one on the drive shaft.

Steve

[Stephen L.]

Re: C2_Universal Joint _drive shaft to differentia

It appears from your photo that you have either the incorrect yoke on the differential or the incorrect drive shaft and u-joint for this application. I assume the u-joint fits correctly on the driveshaft. In either case DO NOT use this combination. The u-jount must fit snugly on the yoke and will be centered by small raised areas on the yoke saddle.

[Joe L.]

Re: C2_Universal Joint _drive shaft to differentia

Steve and Steve-----

Yes, the pinion flange is the style used with THM-400 or 1971 and later Muncies and Super T-10s. It is known as GM #3879208.

You have 2 choices here:

1) replace the differential pinion flange with the correct flange. This flange is GM #3878972. However, it's GM-dicontinued. Plenty of used ones around, though.

2) install a conversion u-joint in the driveshaft. This type of u-joint will have the 3-27/32" diameter on the driveshaft and the 4-5/16" diameter on the pinion flange. These are not available from GM but are available in the aftermarket. A Spicer or NAPA dealer should be able to fix you up with one.

[Steve D.]

Re: C2_Universal Joint _drive shaft to differentia

Joe

Thanks. I would have bet otherwise, but I guess that the one I replaced was a "conversion", because the car was operating well with this yolk and drive shaft before disassembly.

Steve

[Joe L.]

Re: C2_Universal Joint _drive shaft to differentia

Steve-----

I would say that the one you replaced MUST have been a conversion u-joint. There is no way that it could have been a standard u-joint (such as you currently have installed). Virtually all standard u-joints are of "4 way, symmetrical" configuration.

Also, all C2s used u-bolt type u-joint attachment at both ends. The strap type attachment used for 71+ applications, which is what you have on the pinion flange, was never used for any C2 applications.

[Steve D.]

Re: C2_Universal Joint _drive shaft to differentia

Joe

For your files, NAPA part number 210-0134 fits my application. Drive shaft end is 3.23" and differential end is 3.63".

Thanks again.

Steve