Regular Cab Standard Bed Camper Shell Sizing... RCSB vs DCSB?

Hi there, I've got a question that I've yet to find an answer to after scouring the various boards for a while. I've got my eye on a Regular Cab 2008 Tundra with the 6'6" bed. After chatting with a local guy who has one, and has a shell on his, he mentioned that he believed the shell was off of a double cab(not Crew Max obviously) truck.
So, Can anyone confirm that the shells are similar for both of these trucks?

They're both listed as 6.5" beds. I know cab angle can be a bit different, but it's common for Tacoma guys to use various configurations without too much issue.
In my research it looks like only one of the four big manufacturers list a shell compatible with that truck configuration, yet I've seen some random photos on here and elsewhere of Leer, ARE, and even a Snugtop all on RCSB...

 

Also have a 2008 regular cab. We’re you able to find an authoritative answer to this question?

 

I have a 2007 RCSB with a Snugtop cap. I bought it off someone who had it on his double cab. It fits, but is very close to the back-top of the cab. No squeaking or rubbing against the cab, but maybe only 1/4" or 1/2" gap at the closest spot.

 

I actually mounted a Leer cap from a 2013 DC onto to 2010 RCSB. Both 6’6”. The Leer
would not fit my truck. The DC has rounded cab corners. RBC is a bit flatter across the back.
The upper front corners of the cap rested right on the outside edge of my cab. If I’d slid
the cap back 1/2-1” it would not have sealed the back door. So after looking for months,
I’m still looking. Resigned to probably ordering new next year.

 

I just found a 2012 DC Leer 100XL canopy for sale. It doesn’t fit. The lower front will not seal on top of the front of the box. It’s less than 1/4” from the cab corners up top and because it can’t come all the way forward it’s almost an inch behind the rear of the box. So I’m going to sell this to someone with a double cab. Bummer.
So I’ve put an old style 100XR and a new style 100XL both on my 2010 RC. They won’t fit. Really need a reg cab canopy.

 

Following. I’m picking up a RCSB next weekend. Might consider a Softopper until I can save up for a pop-up shell like TOPO Topper.

 

Seems like the Leer fits long. On the RCSB thread a guy just fitted an ARE cap from a DC. Tight
but doable. Snug top looks like it fits different. The only two that I found, that I could actually
put on to try were Leer, one older and the newer 100XL I got. Good luck.