Too bad, I have a HD 3/4 ton one in my shop too. Has the bolt on rear yoke but you can still use a slip yoke on those, they have a beefier back end housing and case
My buddy has one on the floor of his shop, I think it's a universal as well. If interested, let me know and I'll ask him how much he wants for it. He has a ton of s-10 parts as well.
Pete, I had a 400 built for my nova this past year by Larry Kilpatrick (Killer Racing) in London and he told me the 60's 400 have a stronger case. I did help a buddy (tranny guy) install a chev/bop in his '69 GTO, and I'm sure it was a 400, I remember him specifically pointing it out to me.
The cases arent any stronger ,nothing to worry about anyway. Its the direct drum that you want from the 70 and under,they have a stronger sprag and allow an even stronger updated 38 element sprag. If your using a stock or 400 hp and under engine ,I wouldnt worry about what year I got.JMHO.