SB rear seal leak question

He might of been referring to a rope (OE) seal or the common neoprene? black rubber (ish) seal. The crank serrations can make a neoprene seal leak over time. Car quest has the rope seal kit #JV551 (iirc) and the black seals are commonly available. With it leaking profusely you'd likely have to pull the pan and you can drop the crank a hair in the vehicle by loosening the main caps so you can get to & replace the upper seal half along with the lower seal half of course. First see if it is the rear pan seal that is leaking