I can speak in regards to my 1990 Ford chassis/Rexhall Airex- The
manual may or may not be very valuable. The chassis manual (the Ford
running gear) can possibly be had from Helm or other supplier like
Chilton, Haynes, etc. Look up the VIN number. Try:
www.vehicleidentificationnumber.com/
www.cardetective.com/vin-lookup.html
I believe that you will find that the chassis is the Ford E-350 which
was used on a LOT of different vehicles like vans, delivery trucks,
ambulances, etc, so most parts are readily available.

That will give you particulars in a few areas to help you get started.

After that, the best thing for the rest is to contact the various
manufacturers for the fridge, water system, electrical inverter, etc.
and request manuals for those. It will be a bit time consuming because
you need model/serial numbers, then you need to access each individual
customer service department. I have done a few, and they were all
eager to assist.

Finally, look on Amazon Books as there are a number of RV books that
might be of assistance.

If you have specific questions now to help you get going, there are
plenty of folks around this group who have lots of experience and will
be glad to assist.

 From Randy & Val
1990 30' Rexhal Airex

I'd call Winnebago.

Tom J