Needing owners manual for older travel trailer

Did you check Tin Can Tourists?

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=

Extreme Warriors owns the Kit Manufacturing Company's RV division

They MAY be able to help you

208-475-3950

Even if you could find a brand-specific whole-trailer manual it's unlikely to be much help when it comes to the working parts of your trailer.

Owner's manuals were/are supplied for each of the many working components in trailers- those are what you'll need. Just Google "manual for (insert fridge name/model or whatever)" and something will pop up.