I just replaced the impeller on my alpha 1 gen 1 sterndrive off a '90 wellcraft and the driveshaft oil seal is destroyed. it is the seal, seirra #18-2056, that the lower driveshaft goes through to mate into the upper gear case. i have never worked on an outdrive before but am mechanically inclined and replaced the impeller with no problems just curious what i am getting into to replace this seal, as i am 99% sure that the upper housing has to be taken completely apart to reach this seal. any pictures info advice on to make this easier would be a great help. can this be done without dismantling the gear sets inside the upper housing? i don't want to throw a crap load of $ at a mechanic if it is something that i can do myself.