How long is your garage exactly? Have you put a tape measure to it? I have the same issue. A Ford f350 crew cab with standard bed will fit into my garage with exactly 9" to spare....at least on paper. The Ram is about 1 1/2 inches longer and the Chevy is about 8" shorter than the Ford....at least on paper according to their web site specs.
I know one thing for certain. When I got to test drive, I'm taking the truck and salesman home with me and we are going to test park that truck in my garage before I sign any paperwork. Luckily I live 5 minutes from our local auto row so shouldn't be a problem doing that. I don't want any nasty surprises when I get the truck home.