I have a 99 SD that has leather and power seats, it's just a parts truck now. The biggest give away that you have a SD is the lack of any sunroofs. Cause as we all know, there is no good reason to cut 2 holes in a perfectly good roof.
My wife’s ‘99 D1 SD has aftermarket sunroofs. Looking at DDW it was originally owned by Hertz or Enterprise in Chicago. It spent its life in Ca and Tx, so no rust at all.