Need help on lower unit. 20hp and 9.8hp

[sgms18]

I have a 20hp merc that leaks gear oil when you leave it proped all the way up on the latch for a few days. It is a black and blue tiller motor that I rekon is mid 70's to early 80's though I don't know for sure cause there is no S.N.. I'm guessing it's the shift shat seal and wana know is there any other seals I should replace when I'm in there? I have never had a lower unit apart before so I don't really know what I'm getting in to. How difficuul a job is this, are parts and peices going to go every where whrn I pull the foot off?

Next we have a 1970 merc 110 9.8hp that I just rebuilt the carb and fuel pump on and it runs great! But....... now it's not peeing out the weep hole So I guess I gota put an impeller in it. Same deal as above, what am I getting in to?

[stevens_05]

On the 9.8 the impeller is pretty easy. disconnect the lowerend (1/2" nut underneath above prop and 9/16" in rear above lower unit). Then put gear select in rev. and lower end should slide off. then you should see two nuts on top. remove the nuts and the impeller is underneath. maybe an hour of time. good luck