TST Thoroughbred Power Box for Caterpillar Non-Acert engines meaning it fits all E- models and the 6NZ. The instructions are for Pittsburgh Power but are the same and included for instalation. Virtually the same set up as the Pittsburgh Power Box. This is a brand new kit and a used set. I cannot guarantee the used setup working but it was claimed to have worked great and taken off a 6NZ. They do not make this item anymore because of the EPA.For Peterbilt, Kenworth, International, Freightliner, Etc.