No they are not the same size nor shape nor do the mounts line up.

 

One thing to keep in mind for easy swaps, Colorado and Canyon taillights ARE interchangeable. There are posts on here about guys swapping their Colorado taillights for the more stylish Canyon ones.

 

and if you pay close attention to those posts, the swappers have to modify the mounts...so no they AREN'T directly interchangeable. Even the aftermarket taillights have separate part numbers for Canyon vs Colorado.

 

Again I knew about the swappablility of the colorado/canyon assemblies. I didnt know about the silverados's different mountings. I would have thought they would be the same, since they are made probably in the same plant as each other, and ive parked next to them they look like they can fit dimensionally in our light recess, but if they mount differently huh...

 

The Silverado taillights are longer (deeper) and all around bigger. The sheet metal for MS is not made in the same plant as FS, and that is what would really determine if it fits or not. Compare the front and back pics for the tail light of each truck to understand. Even the Sierra and Silverado have not been swappable since the GMT900's came out.
Colorado & Canyon

Silverado & Sierra

 

well, yeah i guess that settled that. lol quite the difference yeah... thanks for the side by sides