I don't know the differences between your '62 and a '66 or '75, but my '66 came with a powerglide and my '75 came with a turbo 350. Both use the same type of yoke as the saginaw and I believe are also the same length. I'd look for the front driveshaft section from an automatic or 3-speed truck, expecting that it would be correct for your saginaw.
I've not had my '72 that far apart, so I don't know but would expect it to be the same.
This is all just a guess....
