I am going to guess on this question, so take it for what it is worth. I don't think Indy 4x would have made 5.38 gears for Isuzus if something already existed for them - no advantage to that. Otherwise, I would like to know where you found out we use Corp 10 and 12 bolts? The GM Corp's are not a 3rd member design and the bolt count signifies how many bolts are on the diff cover to my understanding. Did you find something different? The depth of the pinion shaft from 3rd member to GM housing could be very different, not to mention the possible difference in diameters, and bearing locations.


It is a novel thought though so don't let what I say get in your way - that would be awesome if you found something nobody else has found over the last 15 years! Good luck in your search, man!