2nd Gen cap on a 3rd Gen?

Can anyone comment on if a cap for a 2nd Gen 5' bed will fit a 3rd gen 5' bed?

I would like to have a cap for the new to me truck, but do not want to pay for a brand new cap.
On CL, I'm finding a few reasonably priced used caps, but they're all for 2nd gen trucks.

I've found info on the web that points to the bedsides on the 3rd gen are 1" taller than the older models, but so far, the same resources say the the bed length, width and span between the bed rails are the same.

 

The real "fitment" problem- other than the height- is the tailgate. The third gen tailgate has a "spoiler" which will interfere with the 2nd gen cap door. Even if that door closes, it wont seal.

 

Thanks. That was the detail I was missing for.