I don't know if it makes a difference to you or not. We needed both a shell and a rack on our previous truck. We found that the ARE shell would slip inside the uprights of the shell, but the Lear would not. The issue is that the Lear kind of wraps around the top rails of the bed, and makes it just a teeny bit wider than the ARE.

 

I know you can use Thule roof racks with the Century shell. Woudn't make a difference to me but I checked Google for that. I like having the carpeted insides, goes well with BedRug.