Damn, I think I remember those. They were designed to be used around dusty environments or something. The reduced power kept the truck from pulling in so much air and pluging up the air filter.
If it was an old company truck it keeps people from hot rodding the vehicle. All of our work trucks (brand new f250's) they are limited at 65 MPH and the cruise buttons don't work, you can turn the cruise on but it will never set on any vehicle.