You don't have to remove the tranny but I wouldn't say it's easy either. It's very, very tight and it helps to have small hands and lots of tools, e.g. 1/4 drive sockets. It's good to have the instructions - either from the Haynes manual or the CD. There's a little trick to getting it aligned properly on installation. While you're there it's pretty good time to put on new shifter bushings if they're marginal. It's mostly just very tight - when you first look at it you'll think you need to tranny out.