Finding a decent 600 or 900 series that was used as a tractor will be very difficult. Most of them were absolutely run into the ground. Between the vibration, salted roads, never being garaged and pieces missing that were never replaced made most of them scrap iron. Fire trucks did not have that abuse. Lifting off the fire body, shortening the frame, and adding tractor equipment is nothing compared to hunting parts for a basket case. If you're actually going to pull a trailer, you will want a modern 5th wheel and tractor protection valve and trolley valve anyway. By the way, do you have any idea how much gas a v12 uses?
