Part number 11 on this diagram www.simyamaha.com/category_s/12913.htm?year=27&model=2523&part-category=504 > here is a link to the part itself www.simyamaha.com/product_p/68f-24300-00-00.htm
Which one? The silver fitting? What engine model do you have? This is that fitting www.simyamaha.com/product_p/68f-24300-00-00.htm we have plenty in stock and they are not a discontinued part.
Looks like the same exact boat and engine setup as mine, just picked a Yamaha f70 and f6 for my 2006 Lund 1660 sport. Are you using the stock 13.00/14.00 prop? What mph are you getting? I get 35 with the stock prop, it's not enough prop will easily over rev. Ordered a powertech scd-3 13.0/16.00 should drop rpm a little and gain a couple mph.