We do offer kit PT-A-405, which will work with the OEM HVAC Prep Package fittings; however, the installation is difficult because of access to the fittings. Our HVAC option PT-A-406 works on the ProMaster non-prep package van and the prep package van, and installation is easier. OEM prep package fittings would not be used. PT-A-405 is available if desired, but PT-A-406 is recommended.