You're going to need a different ECM to run the 80E - I recommend finding a later model harness and 7427 (or 6395) ecm, and using that. They are the fastest updating, best supported TBI ECMs and will give you the most accurate engine/transmission control.
Otherwise, super nice ride man, nearly the same underpinnings as my Suburban. I love the old Airstreams, I'm waiting for the right time to buy a towable myself.
Bookmarks