As far as I know all MEP-002 and 003's are built with Onan engines and Libby Welding generator ends. The ASK versions with the sound suppressing housings are often preferred, there are also various trailer mounted versions (laundry trailer, machine shop trailer, dual / single generator trailers, etc.), some of these seem to have special wiring modifications. Things to watch out for, make sure all parts are there, many are missing ground rods, batteries, etc. look out for the hour meters many will have been changed and show very low hours (these tend to be mounted with shiny new screws)