Welcome to the forum.
Newmars 5th wheel group.
1985 LA floor plan
--- 1984 LA brochure
---- 1997 Owners Guide LAFW
Coach's or TT & 5TH WHEELS didn't change that much year to year. Ifyou torn the cabinets and walls out there may have been a paper in one of the cabinets with the information you needed.
You may find a plate riveted to the hitch of 5th with info, that trailers have on their hitch frame up front.
You can ask in this forum 5th wheel forum
they may know where the ID Plate maybe located on a 5th wheel.
Good luck with your remodel place pictures in a thread as you progress.