The GMC Sprint was produced from 1971 to 1977, and is a little known variant of the Chevy El Camino. There were two types of Sprints offered. The base model called the “Standard” Sprint and the upgrade model called the “Custom” Sprint. It was available with an inline L6 rated at 250 horsepower all the way up to a V-8 with 454 horsepower. The Sprint could be had with all the same options that were available on the El Camino. There was even a Sprint “SP” version which was similar to the El Camino “SS” The SP was an option package added to a “Custom” Sprint, with the SP standing for Special Performance, that’s according to the parts books. Finding an SP today is pretty rare, as few were made with this custom package.