They changed, I've looked this up. Some of them were Chrysler spline AND Mopar bolt pattern, mounted to a Chev bell with adapter. I'm pretty sure I've seen photos of some bolted direct to a Chev bell with Mopar pattern, and I know there were some cases with Chev bolt pattern. I don't think all came with Chev course spine input shaft.
I put together one for a guy, was equipped with a "married" tail housing to a transfer case, and was an OD 833. I was amazed, hand never seen one like that.
Another little tidbit, and I dont' remember the year, some of the early 60s GM stuff was available with a FORD all syncro 3 speed, evidently before GM got the all syncro Saginaw deal going.
Mopar bolt pattern, chev input and chev rear tail
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Below, GM input, Mopar bolt pattern, and transfer case rear housing
View attachment 1716059591
