NOTE: THIS IS NOT THE CARSET!
It can be found here:
http://stunodracing.net/index.php?resources/1985-trans-am-car-set.494/
This is my "1985 TA" Championship tracks file. To use drop it in your mod folder, in my case it's in the ASA90 mod folder, so its:
Local Disc Japyrus/NR2003/Series/asa90.cts
Then you must open your game, select the mod using the arrows at the bottom of the menu page, then select "CHAMPIONSHIP", select "NEW", then call it "1985 TA" and select "ALL TRACKS"...fill in your specifics for the rest and then select continue and you are off!
Enjoy!