That jet is a Jacuzzi YJ Golden Eagle, very common for that boat/hull. They have the same internals as a standard YJ and also take the same energizer kit if desired, with one variation being a larger seal carrier and typically the steering cable has to be relocated higher in the hull.
Also unlike a Berkeley E pump these jets can be serviced with out removing the engine. Unbolt the bearing cap, remover the snap ring from the thrust bearings exterior and the whole shaft assembly with bearing and all will slide out the back.
Here's a thread from feb 08 where we performed this energizer conversion, the boat is also a challenger
http://www.socaljetboats.com/index.php?topic=2799.0 its not a very comprehensive thread but it shows the end result.