** Don't know for sure but I would bet they are. They are the same on the advance design Chevrolet trucks/Suburbans. **.
“Pickup bed [rear] wheel wells?” “rear fender wells” - the same as Suburban rear fender wells?
I know nothing about 1960-66.
However, the rear wheel “wells” are not the same on A-D pickups and suburban.
The rear fenders are not interchangeable.
Or, maybe I do not understand what is being called a rear wheel well, and/or maybe I do not understand the question?