Subject: rear drive question..

so, i have an ambo with a 5 speed tranny, and the rear drive is a smooth
side one - i usually dump some fluid in rear end, wait a minute, then
let extra drain out level hole. it would be a lot easier if i knew how
much fluid to put in, instead of the half ass way i been doing it..is it
12 oz or 6 oz?

thanks!