I'm not sure where you initially got your bus serviced, but around here (in Massachusetts) one of the big local Ford dealers is Stoneham Ford (owned by the same people who own Watertown Ford, which is pretty close to Waltham.) I can't say for sure that they've got time or would be interested in working on an older diesel like yours, but I couldn't hurt to call them up and see if they'll take a look at it. (Worst they can say is no, or give you an expensive repair estimate which you don't have to take them up on.) Take a look at a lot of the Ford shuttle buses you see driving around - you'll find many of them with Stoneham Ford mudflaps. They've been pretty good with our 2001 7.3 in our pickup truck. I've also seen them point people to other places for specific work they can't/don't do - so even if they can't work on it, they might be able to point to to someone who can.