Can someone tell me if 8 bolt wheels that fit GMC, and H2 trucks will fit on a 2003 H1.

Yes, but you will lose CTIS. Also, I would not do it for a number of other reasons: H1's have a very unique off set on the rims, no pickup truck rim will match this off set. You will wear out suspension, steering, ball joints, all that good stuff much faster then you would otherwise. Another huge concern is the load rating on the rims. The H1 is quite heave most if not all of those rims are not within the load spec of the H1. There are a number of aftermarket choices for rims in the H1, I would be checking into those. I have a set of polished aluminum Cepek 16.5's on my truck and really like them. Cepek makes some other really cool rims too. Hutchinson makes some great looking stuf as well.

I am selling the rims on ebay. thanks for the information.

What are they? The 2 piece aluminum wheels?

The wheels are Mazzi and the tires are Nitto Grapplers LT305/55R20.

I had them on my 2003 H2 for 5K miles, then sold the H2 for my 2003 H1.