Hi! I just bought new rear brake pads and the manual says I need new drum gasket, o rings, felt seal and some other seals which I cannot find..Are these essential?

 

Not really, they are for water not entering the drum housing. Even new I never seen a water tight drum brake.
Infact I know people who drill a small hole in the bottom of the drum housing to allow the water to drain out to prevent freezing.

Put some silicone in the curve if you can't find a o-ring seal.

 

There is a drain hole at the bottom of the drum cover actually. I wonder if I should try and make a gasket for the drum cover, that shouldn't be too hard.

 

I believe the O ring in question is on the axle but I haven't taken it apart just yet. It says to install a new grease seal and felt seal around the brake cam, again, can't find any part #'s or anything. So not needed?

 

Plenty of different sheets of gasket material at any auto store that you can use to make a new gasket if you wish. We kept sheets of thick gasket material along with felt sheets for this one reason.For gaskets that were NLA. You can trace the old one or if it's shot just trace around the housing.Either that or use a good gasket eliminator to at least try to keep dust,dirt and at least as much water as possible out.

 

Later models have an o ring round the tin cover seal. With any of them run a smear of grease round the mating surfaces, tin and aluminium plus water creates corrosion and the cover sticks fast to the backplate if you don't. Soak the felt cam washer in oil before you put it back. I have used a twist of sheep wool to replace missing ones. The water seal in the centre of the cover should be in good condition and greased too. The collar that runs in it is always worn and probably why they leak, but is no longer available anyway.