The room for the engine is the same in small and large trucks, same distance from radiator to firewall. The fenders bolt to the cab just the same.
The big truck fenders are different enough for larger tires fit in them, a larger wheel opening.
Not sure what you're intentions are but pretty much the one advantage of the big truck fenders is to fit large wheels, 36-38" or so outside diameter works and looks good. They look funny with tires about 33" or less. Roughly speaking, your opinion/ideas of tire diameter and fender opening may differ.
I measured big and small truck fenders on the truck to the inside where the tires might rub them if an axle were too wide, or wheels stick out too far.
Small truck 68" width measured inside the front fender lip at bottom of opening, same both front and back edges.
1.5 or 2 ton AD front fenders (on the truck) 72" wide inside to inside of the lip at the bottom edge both front and rear of the wheel opening
So the big truck fenders stick out about 2" more each.
Grigg
