Re: 135HG 1977 lower unit/foot sealant?
Assuming you are describing the two piece lower unit with thrust pin prop and 18 spline prop shaft:
The gearcase is sealed to the mid unit with a large O-Ring in a groove. There is a steel bushing at the front stud, and another O-Ring there to seal out any water that may work its way past the stud seal up top.
Just behind the front stud, again, up top, there is a seal that the shift rod passes through. It is the same seal used on all year large Chryslers and all larger Force engines up to about 1989. You may not see it because it is countersunk into the aluminum casting.
However, the parting line--where the lower unit bolts to the midleg with seven bolts never has a seal and no sealant is necessary. SOME old Chryslers did have a shift rod seal to supposedly stop exhaust gases from exiting through the hole but that was quickly discontinued as ineffective and redundant--read unneccessary expense.
This lower unit is a "three bolt" lower because it has three studs attaching the gearcase to the midunit. Earlier gearcases only had two--front and rear. You can see the countersunk relief for the shift rod seal behind the front stud. There is also a smaller O-rings under the thick washers at the top of the center stud to seal the whole lower. You can see the relief for that too.
