a picture ...

and a closer picture ...

I don't see any gasket shown anywhere, nor do i see any obvious sealing compound on it when I look at the truck closely. a gasket would be pretty obvious on the parts drawings, so i'm assuming it should be sealed with a sealing compound of some kind ... and if i read the manual right, that is actually the case. I have just two questions ...
1) do i have to take the axle housing/swivel ball/etc right off the truck to re-seal this or can i get it apart enough on the vehicle to seal it?
2) what sealant should I use?
thanks in advance.
jim