How do you know if you have a numberd 1987 359 peterbilt?

All numbered 1987 Peterbilts will have a brass plate riveted to the glove box on the passenger side. Only certain 359's got numbered in 1987. Not all of them. They had to come from the factory with vortox stainless air cleaners, big bumper, and several other options in order to be classified as a numbered truck.