71 Cuda project car has a B body 742 rear in it. No fluid since the chuck was changed by the previous owner. The rear brake shoes and hardware were all brand new, so I suspect he also did the axle seals. When I fill this rear, where could I expect leaks?

Out the axle ends or at the diff itself if he didn't use RTV or a gasket. I've swapped chunks without replacing the seals and got lucky and they didn't leak.

I edited my post.