Ron,
That is a difficult thing to find.
You will need a rag, wire brush, flashlight/droplight.
Lift up the rear of the car, place a chock at opp front wheel, parking brake on, jackstand to hold up car.
Crawl under in the, shine light at the differential, use wire brush to brush off the bottom of the diff to remove the gunk/dirt/ mud/ crud and wipe clean with rag. look at the surface with flashlight and find the #'s.
There should be some faint numbers stamped. Your car I think has the 4:08 rear end.
Walter
1967 220SL-diesel
