[Mike C]

When GM switched to the 5 lug rim on the 2x4 trucks in '71 they reduced the pilot hole size. The 4x4 kept the old larger pilot. In '88 on the 1/2 ton 4x4 and light duty 6 lug 3/4 ton trucks they used the same small pilot hole as the 2x4 trucks.

So, the 6 lug 4x4 rims from '88 and up will NOT fit an earlier solid axle truck. But the 88 and up 5 on 5 2x4 rims should work just fine. And the 8 lug wheels keep the same pilot and lug pattern through 2010 I believe before it went metric.