Re: 1975 Mercury 650 lower unit assembly

[billw]

No, they’re not all the same. Reverse is a bigger ID and OD than forward. They come as a kit with maybe five or six different sizes and you have to measure for the right size. This can be tricky if you don’t have the right tools. The good news is that the reverse shimming is far less critical than the forward and pinion shimming.

I can’t believe those have gone NLA. I even checked Mercury’s dealer site. If I had a nickle for every one of those old shims that I have tossed out…..Anyway, there are still 3 on eBay and probably hundreds more in dead dealer stock around the country. Part # 15-20927A 1.

Long live American manufacturing!