To add to what Wrenchbender says, '71-'87 (pickup) or '91 (Blazer and Suburban) will work. After '88, the backspace is too deep, and the wheels wil rub the drag link and tie rods. Also, stay away from wheels for japanese trucks. They wil bolt up, and the 7" will clear the tie rods (barely) but they will hit the drag link on a left hand turn.
I also like the Ralley wheels on the older trucks, either the Corvette ('67-'82, available aftermarket in 6 lug) or the Blazer ('73-'91) style. I have the latter.
