[1976gmc20]

I guess I have no idea what 5 hole wheels the GMT400 2wd models came with. Somehow I thought they were 16" five holers?

Suburbans are awfully heavy and the half ton squarebodies with only 15" wheels (5 or 6 hole) were in my experience hard to keep tires on because you could only get up to C range (unless maybe you special ordered?). So what I was trying to do was economically convert a 6 hole squarebody to 16" wheels and bigger E range tires to withstand gravel roads. I used to go through LT235/75r15C tires like they were kid's balloons - pop, pop, pop!

The expensive discovery was that 6-hole GMT400 wheels will NOT fit on the squarebody 4wds even if you cut out the center hole to fit over the hubs. I suppose the reverse is possible although the wheel & tire would sit 2" farther out and the center hole would be too big so all the weight would be on the lug bolts.