TheP21A-T802 kit is designed to replace Espar heater model 25 2069 05 with Digi Max Controller. It is a direct replacement for the Espar Airtronic D2 bunk heater that plugs directly into existing wiring harness and uses existing fuel system, ducting, exhaust and combustion air and hardware.
The P21A-T806 kit is designed to drop in to a new Kenworth truck that arrived at dealership and was missing the heater. The truck is wired, and all accessories mounted but, no heater. This would plug into existing wiring harness.