Needing owners manual for older travel trailer

I recommend getting an older edition of Livingston's RV repair book so that it covers the same vintage of appliances found in your TT. Here is a link to some 1989 editions for sale via Amazon.
link to many sellers for this item

Here is a link to the book at Powell's. I've dealt with them and have found their service to be excellent.
http://www.powells.com/s?kw=Livingston+RV&class=