[hatzie]

I ran a set of 2000 C2500 steel wheels on my 1976 K20 for a while with 265/70R16 tires. They didn't rub at all.

The T400 and later trucks ran Metric lug studs so you can't use the stock 88-2002 dual thread lug nuts from your donor on your 1974 SAE lug studs.

Not sure whether the dog dish hubcaps fit the 88 and later T400 steel wheels.

I read somewhere that the wheel to lug nut taper changed in 1988 too but that's an unverified rumor. It's not a bad idea to replace the 1974 lug nuts along with the wheels anyway.

My K20 had 9/16"-18 lug studs. You can evilbay four corners, sets of thirty-two, 9/16-18 dual thread lug nuts to hold on the 1988-2002 wheels. The SAE inner threads with 88-2002 outer threads let you thread the plastic hubcap retaining nuts on with the stock 1973-1991 lug studs. The plastic lug caps are nice to keep dirt out of the threads even if you don't run the hubcaps.