What was the TN law for requiring Water Vapor Shields/Barriers when this model was manufactured in 1997? Have seen a DW with the cheap wood siding look that has no water barrier between ext siding & the insulation for the int walls. People have a 1994 Oakwood with water barrier/shield have no problems;same type ext siding.?

That's almost 20 yrs. ago. Doubt there was a law regarding vapor barrier. You mention "interior walls"-did you mean exterior walls? Why insulate an interior wall.

... Why insulate an interior wall.

OP wrote "between ext siding & the insulation for the int walls. " Obviously, interior walls don't have siding, so I think OP was referring to the portions of the exterior walls inside of the exterior siding. In other words, the portion of the wall interior to the siding.

I agree that it will be next-to-impossible to find what, if any, regulations may have existed some 20 years ago.

That was my thought too but thought I'd make sure.