i know of a few guys who preferred a built 5 speed over the 6 speed in their 03/04's simply because they are track only cars, so it's definitely not unheard of. To the OP, does your brother know for sure its a 5 speed? was reverse at the bottom? and althought it wasnt as simple as bolting in the T-56 in my car, it definitely wasn't much of a hassle. And i doubt he was looking for cheap replacement parts as the 99/01 tails would cost a hell of a lot more than some regular mustang tails.