it's certainly an Impala SS. I forget the exact factory colors, I wanna say it came in black, burgundy (maroon), and a very dark minty green. there could've been more in the '94-'95 models, those were slightly different from the '96, which is arguably the best one, because they were converted Caprices. the Caprice was a slow seller for civilians, it was mostly a fleet car, and American cops even still today swear they were the best ones ever made. I wanna say the C-pillars were changed for '96, the C side windows didn't curve inward, they angled diagonally to the bottom.
I don't know anything about TDU moding, I'm not sure if you can create wheels for it or not, but I think I had the same rims in .z3d for one of our Firehawks.
only major problem I have is with the Impala badge on the trunk, it's way too big. that, and you should probably change the model year to 1996, cause that's what it is. :)
great model, I think Pumbarz used to convert to GTA for us years ago, he's pretty good.