From what ive gathered in looking for one myself for my farm truck they are different..
I had a top off an 03 I ran on a 01 and it fits my 10. It's a Leer Q100 I think, full side glass. The angle from the cab to the cap has a slight opening gap from the bottom to the top, but mine fits, and covers the bed. I kind of prefer the gap, cause the new caps are so tight against the cab one 1/2" off and it can rub your cab