I installed one.....
on my 37' Legend with a 3HM35 engine a year ago. Can't say what size is right for your system but mine took a 424Ysize. You would have to take many measurements as described in catalogs for the product. Once you have the right one, installation is straightforward and simple.. disconnect the coupling, insert the Saver and rebolt.. I did not electrically reconnect the components. I read somewhere that if the shaft components were electrically isolated, barnacle growth would be less. The jury is still out on this. I have not seen any difference in the operation of any electrical components as a result of this but I wonder what would happen in the event of a lightening strike. Since I was hit once 12 years ago, I guess I paid my dues?? I did not shorten the shaft for the installation. An extra inch should not matter as long as the distance has not already been extended for some other reason and is now excessively long. The actual results are a little hard to quantify because I installed the Saver as part of a 'complete' 'shaft job' where I installed a new cutlass bearing, centered the shaft in the exit tube, moved and aligned the engine to get a better alignment and replaced 2 motor mounts. The whole thing came out really good but as i said, hard to quantify the actual effect of the Saver itself.
