jimvette59 ... I asked for a driveshaft that was 61 7/8" long (ceter of u joint to center of u joint, with 3/4 " of slip. It came out closer to 61 5/8", with about 1" of slip.
I had it made because there was no power train in the truck when I got it, but it is "stock" setup with an 8Ba and a 3 speed top loader.
There is a different seal, from a C4 maybe? that has a rubber boot over the exposed part of the splines, and a flange that sets it right at the back of the housing, that can be used. A friend got it based on measurements at a Carquest shop, but he doesn't have the number. I think I will try to find it next time I need one. Not sure it would help you as the actual seal is still about flush with the face of the housing.