First , that is not a 3000 series, & I don't believe the 3000 or 2500 series was available in 1990. I can see by the windows
in the picture that they are single pane windows
( dual pane appear somewhat recessed ) so that is what we now would call a 1500 series. About as light
as you'll find in a BFTC. look for a sagging roof as many then didn't have factory AC, & may have not had proper bracing added when it was built.
FYI, a 3000 series had a molded front, rear & bottom section with flat 'sandwich' sides & a rubber or (later models) FG roof section. VERY well insulated, but not a true FG (as we consider them) with a clamshell top & bottom section, as is the one pictured.