10 bolt axle help

[1989bmw535i]

Hey guys, I'm new to this forum but I had a question, I have a 1976 chevy k20 and I'm wanting to put some new ball joints and wheel bearings in the front axle, to my knowledge they didn't put 10b's in these trucks till 1977.5? Just trying to figure out what parts I need because napa can't figure out if the parts are for a 10b or a Dana 44... thanks! P.S. I was told the truck was rebuilt a while ago and I'm sure they swapped axles around...