Bucket,
I take it I can't swap in the Dana for the Eaton. But it does sound like I might try finding a GMC rear -- or does that open another set of problems. Forgive the dumb question.
Jim
not a dumb question. if you can find a dana for a coil setup that would be easiest and yes, it would be a direct swap. don't know about any differences in drive shaft length though.
otherwise, i know guys have fabbed the appropriate brackets to make a dana fit the coil/trailing arms like the eaton.
go to here for lots of info regarding what you are exploring:
http://67-72chevytrucks.com/vboard/