I've cut perches off and rewelded, , but only after dropping pumkin (removed axles first) or just popping rear cover on the other (like a Dana in a race car), to drain rear end lube out before welding.
Just not sure the heat on the inside of the axle tube and lube will play nicely?
I have done some short duration welding in stitches on '07's oem shocks I was shortening solid steel bottom stalks (not welding to shock body itself) on … to lower my '07, but I cooled those shocks with water between stitches. I suppose same could be done with perches, but I'd want those burnt in good.

 

Correct me if I'm wrong but isn't a 76 divorced t-case?