I made my own for my Saltare. Foudn teh biggest off the shelf heater core I could (I believe it was for a '79 Ramcharger) and made a box. Welded 2x 4" tings on teh back for blower motors to push air through it, and 3x 3" rings on the front for the hot tubes. Piece of cake. Kept the in/out low on the box how I mounter it so winterizing is easy, but disconnect the hoses from intake and suction side fo raw water pump and blow through the hose until nothing comes out. Seat heaters are a great addition too!