Alot of the rodders will use the wider opening fenders to get a different look, but they definitely wouldn't work for a stock restoration.
A quick way to tell the the difference between 1/2 ton fenders and "big truck fenders is that the "big truck" fenders DO NOT have an "notched" opening on the front of them for the bumper to mount to the front frame horns through. The "big truck" fenders go over the bumper mount horns and the bumper will mount under the fenders.
If they are laying on the ground at a swap meet, look for the notch. If the fenders have a notch, you found some fenders - if if they don't have a notch, keep walking because they just won't work.
