Limited slip diff., how to tell
 

This is another question for a friends car. I am going through the car, checking the brakes and changing the fluids.

Per the FSM and owner's manual the rear diff takes 90W gear oil, unless it's a limited slip differental. In that case it requires a "special hypoid oil"

How does one tell which diff. the car has. The car is a 1974 450SL

I will add that when playing around with the brakes on the back end, I found that I was able to rotate one wheel, with the other on the ground. this of course leads me to suspect it has a limited slip diff. If I am correct, what is, and more important, where can I get this "special oil"

Thank you again.

Safely raise both rear wheels and chock both front wheels. Turn one rear wheel while observing the other. If the wheel on the other side turns in the opposite direction it is an open differential as opposed to limited slip.

I'm sure there are MB's with limited slip differentials, but I've never seen one.

N0 USA 1974 450SL came with a limited slip differential,

If you could rotate one wheel with the other on the ground its an open diff, you should have felt some resistance if it were LSD.

Not sure about the R107's, but there should be a metal tab on the right rear lower bolt that holds the cover.

I don't think you can spin one wheel fast enough to overcome the limited slip clutch. Now positraction, is a different bugger.

Thanks. Now I know I can just get regular old 90W gear oil.