Rear axle/diff housing

Currently my rear end is heavily rusted. I bought a Barnes Off-road weld on cover a few years back in anticipation of having to replace my pumpkin cover. Well now my rear end is leaking like crazy, & the metal all around is also crap.

I'm curious what's the difference between the housing on fgt 2wd rear axle housing, vs a 4wd housing??

I know they are 2 different part numbers..
But I'm curious what the difference is. There are way more bare (rust free) 2wd rear housings out there, then 4wd.
-thanks in advance-

 

I'm pretty sure they're the same. Maybe a difference in the driveshaft connection. The sequoia ones are different though, so dont try that unless you're after rear discs and a lot of fab work.

 

They are different part numbers from Toyota..

There has to be more then where the pumpkin mounts to the drive shaft.. that's not even part of the bare housing..