I did my 2004 340 Sundancer 8.1's myself. I bought parts at ebay. I mis-read the information on the part numbers and bought the standard elbows. My 340 needs the tall elbows(no risers), so I had to buy those. Now I have standard rise elbows that I can't return.
So....If you know anybody that can use them, they are brand new! Don't make my mistake when buying your parts.
I replaced everything with new, including the temp sensors. If you've not done the job before, there will be some instructions and references that do not match the Maintenance Manual. New style installation uses head bolts, not studs with nuts, same with the elbows. The torque may not be listed in the manual.
I also installed a freshwater flush system that includes a connection to the Gen & A/C pump. I can flush my engines, Gen, & A/C cooling water circuit without opening the hatch. I do as Wingless after each running: fresh water, then SaltAway.