The Early Volvo jets were built by NAMJ (jacuzzi) and were YJ's for all intents and purposes The later ones like Gwexler were built by Dave @ Legend Jet drives ,Dave is /was a former Berleley Worker (engineer) Very nice piece in terms of construction Orings vs gaskets etc The jet is very similar to a Berk "E" "insert style" Jet , Weve sold parts to.. and serviced them , most Berk parts and "add ons" will interchange (or can be easily made to work! Tom