Alan pretty much summed it up. The EPA is enacting OBD2 standards on 8500-14,000GVW starting with the 2005 model year-less than a year away. A quick way to tell if it is non-OBD2 is if it has 8 lug hubs- most that do are over 8500GVW. 3/4 ton trucks are split,... Login to read more.