[BBEEP]

The bigger fenders are wider, longer, taller. They acually sit higher where they meet the back of the hood. The wheel opening fit the Envoy wheel better. Doing it the way we originally tried, we would have had to change the opening as well--or raise the front of the truck to clear. The 52 Burb built by GM was done that way. When I showed them the pics of how we did it, the said they wished they had thought of that. Their TBSS frame had to be lengthened to fit the Burb. Mine didn't.
If I was to do this again, (and probably will) I would get a 2wd and just put a TCI or some similar complete aftermarket rack & pinion set up in it. It probably would cost about the same.
They are 1 1/2 ton fenders. There was enough of the 1/2 ton fenders to simply 'make' them fit with a little cutting, stretching, etc. The big fenders were 4ish inches longer, in the opening. Wouldn't be close to right . . .