Re: Can 1957 mark 30 parts be found?
And oldmercs.com. The lower units were the weak link in the Mark 30s, as the unit was essentially a 15-20hp lower unit with a beefier driveshaft and pilot bearing. The gears didn't hold up well with modest abuse. Also, the drainage at the rear of the gearcase where the water intake is was easily plugged, resulting in many cracked housings. Factor in shafts that rusted over time and you had water getting into the gearcase itself, causing its own issues. The end result is that there are quite a few Mark 30s out there missing gearfeet.
FYI, the gears and housing from a Mark 25 will work with your Mark 30. You'd have to swap in your driveshaft and upper bearing. Mark 15 and Mark 20 housings look similar, but have smaller exhaust outlets and can restrict breathing... Might be able to make one work by opening it up with a Dremel...
- Scott