pics would help.....i have a jacuzzi wj on my boat, wj has 4 bolts connecting the nozzle to the bowl. yj is one piece bowl/nozzle. at least that is how i understand it.

I need to ID my Jacuzzi pump so I can start ordering parts. There are no visible numbers on the outside of the pump. It is on a 1978 California hull that had a 455 in it originally. That seems to be a popular combo for whatever reason. How do I tell a YJ from a WJ ?

beyond the Id tag ,the external "Id" differences are fairly simple one of the most obvious is the rearmost portion of the bowl , a WJ has a Grease nipple (zerk) deadnuts in the rear top of the bowl just ahead of the steering deflector , The YJ has an "inset" cast device about 6 inches long (for nozzle trim) attached with 6 3/6's allen head bolts in the same area just ahead of the steering deflector The WJ is the "Mixed flow jet the YJ is the axial  flow feel free to post up or call if you have more questions and welcome to the boards Tom

more info here if you need it ..
http://jacuzzijetdriveparts.com/

KT On the YJ The Energizer makes a big difference in performance on the WJ , not so much the Wj is already very similar to a Berk in design the Big advantage on any energizer is when the prospective parts it will take to repair "balance" or outweigh the cost of the kits and of course when an enegizer is installed theres the added advantage of being able to use Berk Bolt ons (droops , nozzles etc) Re whos is best , The only folks that currently produce an energizer is American Turbine and they average around $1600 to $1800  on the market Tom

Do you sell American Turbine? or other? I will give you a call on Monday. You were a big help with swappin out my Olds for a Chev. I was up in Bend, OR. Ring a bell?

Yes We are Dealer/Distributor for A/T Dominator and Legend amoung others Happy to help ! Tom