First off I'm the new guy here, looking to see if I can find help here. I am the engineer for my fire station and one of our squads is a 1990 Suburban 2500 4x4. I do have a few questions and I hope this is the right place, First off we have a rear heater its all beat up, was wondering is its easy to replace / find a new one? Tires are going to be on the list to get, is there a bigger size that would work? Was thinking of a little lift, what would be decent without having to change awhole hell of a lot. In advanced thanks for the help!