In past experience Pontiac and chevy use different U joints so the yokes on the chevy shaft would have smaller bores in them, plus external vs internal snap ring retainers.
FWIW, friend of mine had a 64 chevelle 283 4 speed and as has been noted it had the rubber harmonic sleeve, after he wrecked it I got the driveshaft from it to use in my 63 Tempest transaxle conversion because I was using a chevy saginaw 3 speed. I had also installed a 62 corvette rear axle in. The hope was it would be the right length, and right size U joints, however it wasn't.
I had to use 2 driveshafts to make one. It was one of the only GM driveshafts I had ever seen with the harmonic rubber sleeve between 2 different size tubes. I believe it was only 1964 A body chevelles that it came in, and possibly the 215 Powerglide equipped Tempests, it surely could have been used in a few 65s, but I never ran across one that I recall.
Hope that information may help............
