With Bill1947's permission, I'm releasing the template I used to make the cars. NOTE: I use Paint Shop Pro 2018, I don't know how well the PSPimage template will work on earlier versions, and I don't know how well the PSD will work in Photoshop. I recommend downloading the Airstrike font from dafont.com, I used that for the numbers and names.
If you're painting anything but IROC cars, I recommend using Bill1947's original template, which I found at The Mod Squad