Leaky seal replacements?

My R80G/S has leaky pushrod seals.
I cannot find good info in either Haynes or Clymer manuals about replacing them.
I am assumming that when I pull the cylinders off I must replace the cylinder base gaskets, and head gaskets as well, or is it possible to pull the cylinders without removing the heads?
Any tips or tricks for this procedure?
Also it appears I have an oil leak in the rear differential, and it seems to be coming from the brake stud??? is there an o-ring in there?...

i think your bike is probably too late a year to simply tap down the push rod seal retaining rings to get a better seal, so you'll have to take the cylinders & heads off. not a major job really.

no gaskets, 'cept head gaskets, just O rings under cylinders. renew along with push rod seals.

check valve guides while the heads are off. possibly change exhaust valves. costs mounting

Thanks cookie,
Yes its an 1981 and have already tried pushing down the pushrod seals.
The bike sat for a few years and so alot of the seals are leaking.
Just learned that there are indeed o-rings on the brake cam, so that should not be to hard of a replacement.
Cheers, Peter

Get two carby gasket sets - replace the seals in the carby. And while your there replace the needle and seat in each cardy - they ware and give poor fuel economy.