Difference between gmt400 and 800 axles and diffs?

Blackout

Dat Rust Bucket
Dec 18, 2015
121
11
0
West Michigan
My 03 1500 z71 (10 bolt) has the shitty open diff and I noticed it's getting kind of loose, and I need to change the nasty fluid anyways.

I have a 98 10bolt with a 30k g80 sitting in it out of a truck I threw a 14 bolt in and sold. When I drove the truck before the swap the g80 worked flawlessly and was nice and tight . I'm thinking about putting a locker in this truck to help a little more in the snow and off road without having to switch in and out of 4x4 all the time.

That being said, do I need to swap both the diff and the axles over? One or the other? Or is this not even possible and Im stupid for thinking it is?