I just went through the process myself. So their is a seal under the water pump, a seal around the shift rod, an o ring between the two halves of the lower end if yours is a two piece, a prop shaft seal, another o ring aaround the part that holds the propshaft seal, the screw for the shifter pivot point also has an o ring i believe. The seals on the drain and fill plug can leak also. The best thing to do is pressure test the lower end to find out where it is leaking, someone hopefully can post how to do that step by step but basically you submerge the lower unit and apply air pressure and look for bubbles. I just tore my lower unit down and checked out the bearings and installed a seal kit. The Kit for my 105 was sierra part number 18-2631 it should be the same as an 85hp., it costed about 35$ shipped. All the seals are a standard size so a bearing and seal shop can get the for you i opted for the kit.
