In the glove box on the "Service Parts Identification" tag there will be a "5S6" to designate the option of the Indy Pace Truck options. Also in the GM Herritage online manual if you scroll down towards the bottom to page 67 you will see more information on the pace truck options and codes. I will try to put a link on here to the site.
https://www.gmheritagecenter.com/doc...olet-Truck.pdf