The fenders are the same on a 1/2-, 3/4- and 1-ton. And most the rest of the front stuff too. I say most because 1-ton front bumpers are different.
I've seen pictures of fenders being widened, but they were on an Art Deco truck, not an Advance Design (New Design if yours is a GMC).
If you go all the way back into the 70's you may be able to mitigate some of the extra width with your wheel choice. I've seen wheels from a 2000-ish Dodge used where the issue pretty much went away. Unfortunately I never figured out exactly what Dodge the wheels came from.
