Long shot but does anyone know if, and where, I can get the original plans for my house?

I inherited my dads house and it was built in 1975 by trendmaker.

There are a few odd things about the house that makes us wonder if it was originally used as a model home. Things like a bedroom that has a closet not finished but two sets of plugs sideways along the wall in the closet. And another room that we are thinking may have been used as an office for the model home based on the two sets of doors, and the fact that it has a closet.

Also when looking at the history of the home it was built in 1975 but the first person to buy it didn’t buy it until 1985

I know it’s a long shot, but does anyone know if the city keeps records like that?