rear end axle....wtf?

All-right...bear with me here....

When I sold my Caprice, it had a Roadmaster rear installed with 2.93 rear gears (8.5 housing). The rear previously installed (also an 8.5 from an 87 9c1) had 3.73 with a welded carrier, but I had snapped an axle. So, the PASSENGER side axle was broke and missing, but I included the housing as a spare.

The kid that bought the car wanted the 3.73 axle in the car, so he "supposedly" swapped out an axle from the 2.93 rear into the 9c1 housing....only I dunno what the hell he did, because that is not what happened!

I go to test fit my wheels with the drag radials today, and the PASSENGER side (the side that was broken at one point) bolts right on no problem.

I go to the DRIVER side, and the wheel doesn't fit?! After closer investigation, I realize for some reason the kid installed an axle with the regular old chevy 5x4.75 bolt pattern?!?! He torched out the bolt holes in the drum to get it on the axle!

So here is where I am at....I obviously need to switch one of the axles.
I would love to have traditional chevy 5x4.75 all around instead of the big 5x5 pattern in the rear.....but where the hell did he track down an axles with that bolt pattern? I didn't even know you could GET a 8.5 rear assembly with 5x4.75 pattern?!

Also, I know the pinion is slightly offset to the passenger side....but are the axles two different lenghts? (as in left and right)?

My only experience rebuilding rears was at uti. And yes, axels were different lengths. We were using GM rear ends too. No idea what the specs were tho.