stubs are shorter in the Fords. 11 5/8" vs 12" if my memory serves me. Can cut down the GM ones to fit in the Ford but in doing so you lose the snap ring groove. So then you have to have someone machine in the new the groove, not to mention cutting them isn't the easiest task(not that is killer). Lockouts can interchange.
Yukon 35 splines for Ford 60s aren't really expensive. $109 a pop at Bronco Graveyard last I checked(which was like last night).