Did you see this info previously, and here's some references to check and explain. http://www.stovebolt.com/techtips/driveline/setup/index.html
Originally Posted by Grigg
...a u-joint is not the ideal coupler because in this case it wouldn't have any angle to operate through, it'd be straight. A U-joint with no movement soon wears flat spots on the needles and corresponding groves on the trunnions. I suppose if it's a bushing type u-joint (no needle bearings) there is more leeway, still though that's not as good a junction in this case as a straight splined coupling would be.

Grigg

The shifter bracket looks much like some of the later Spicer auxiliary shifters, they may have that smaller ball size.
You could machine or have made what you need to fit if you can't find an old one.

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-