I'm not sure on the 30's trucks, but later, the shape of the front part of the fender and the size of the wheel opening was different between light trucks and big trucks, meaning the 1/2T fenders wouldn't have enough clearance for the bigger rim size on the 1.5T - I think the Maple Leafs were re-badged GMC's

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir
"When we tug a single thing on an old truck, we find it falls off" ~ me
Some TF series details & TF heater pics