Congrats on your recent acquisition. With the usual very low mileage of former fire trucks, your truck should have be in pretty good mechanical shape with lots of life left in it.
While you ponder on questions you need to ask in the various Tech Forums, based on your indicated location you are right in the midst of the The Southern Bolters
region. Check out that forum and introduce yourself in there as well. They have a bunch of upcoming events you may want to check out too.
You may also want to checkout the Big Bolts
forum as you truck fits right into that category.
Looking forward to more conversations in the future.
EDIT: I see Miss Peggy beat me to the 1st welcome - haha. Just me too slow on the 2 - finger typing speed.