Don't need w/ PS is correct in one sense. BUT, if you lose your PS while underway , like I did when I popped a hose, you are in for a tough journey. Ater the hose failure, I disconnected the PS belt to get home and not toast the pump, and my boat pulled like a bear to the port for 20 miles. It was a fight the whole time, that could have been minimized if there was a tab on the drive.
It is obvious that the tab also reduces the work load on the PS when everything is working properly. I went to the tab, even though Mercruiser say's it's not needed. The way I see it, if it reduces a pull to one side, it reduces strain on the PS. There is the potential it is reducing the load on the pump and saving a few horse power in the process and maybe saving a little fuel too.
Especially these days, saving just a little fuel is a good thing. I may be way off base here, but the tab is on there anyway.
