I purchased mine off of a Tundra owner and it fit perfect. He bought it new for his truck so I if it works from a Tundra to a T100 it should work the other way around. The cab aligns perfect. Both the T100 and the Tundra have the same cab height from the top of the bed to the top of the cab. I think the major difference between the 2 is, the depth of the bed (deeper on a Tundra- but irrelevant for a shell) and the Tundra's bed is 1" wider (because the rails are wider). The shell though did NOT show that difference. I would say go for it. GOOD LUCK!