Rearend ?

Unknown

In the 1929 Hudson Instruction book it says to fill with oil up to the pipe plug. Is this the pipe plug on the rear or the one that is in the front that is a "L" with a pipe plug on the top ? This one seems like it would be to much oil? I also have alot of oil getting thown from where the drive line goes into the rearend while driving and leaking a little when parked. I see what looks to be some type of a large ajustment nut in that area and not sure what it does ? Is there any repair manuals out there that covers all this stuff ? I see manuals but seem to go back to the 40s and maybe a little 30s. Also what weight gear oil ? Thanks Ron