The Eaton rear is big and noisy and big. It's a hotchkiss housing with a access cover, the best of both worlds. The Eaton was a 1 ton rear found on old Chevy trucks, you might find out more about it that way. I know someone with a 67 Blazer, he's got an Eaton under it and 40"s.... it is strong.
The 60 is most likely a better bet, more options available for it as it's still in use today.