We have brought back our K20 housing w/optional filler neck. We have made some changes to the design.  We have kept a lot of the basic features like the 1/8NPT temp sensor port and recirculation fitting. The housing seals to the head using an o-ring to ensure no leaks. We supply the mounting hardware and plugs for both ports. We changes the assembly process by using threaded ports and o-rings to making switching between filler necks and fittings quick and easy. The filler neck offers a 2 position locking pin. This is designed to locate the filler for standard motor setup or for lean motors.