Welcome to the Stovebolt!
Fit as in look like a 1/2-ton truck? No. Fit as in bolt on with a minimum of fabrication? Actually I don't think so, but its worth looking a little harder to be sure.
I know the 400 series cabs are similar enough to make it bolt up, or at least all the lines match... I have a 400 series GMC front clip currently sitting on the front of a 1-ton Chevy and the 1-ton Chevy is the same as a 1/2-ton. 500 series might be the same.
But I believe the 600 and larger GMC trucks have a different cab design. I know the 900 series are different. If you can find some pictures look at the lower cowl area where it meets the fenders, and the lower parts of the doors.
This is a picture of a GMC 970 that appears at shows in my region. I've seen it at ATHS Brooks I think.
GMC 970 I just did a quick search through the gallery here and didn't find a good picture of the big but smaller trucks. You might look at some pictures over at
www.OldGMCTrucks.com and see if you can find a good picture there.
