w116 300sd differential oil

[xaliscomex]

Own a 1979 300sd and need to replace the differential oil.  Would like to know what type of oil I can use that is equivalent to the mercedes dealer.  Is anyone here familiar with this car?  Would like to know if it is equiped with a Limited Slip Differential(LSD).  I know that there are gear oils that I can use and all that depends on wether or not it is LSD.  Someone once told me that if I lift the center rear of the car and turned one wheel one direction the opposite wheel will turn the same direction and that confirms an LSD.  Can anyone qualify that statement?  Would appreciate recommendations?

[WGB]

LSD was never fitted to Diesel model that I know.

Only car it was fitted to as standard was 6.9.

There is a plate near the filler plug that will say if LSD is fitted.

If your diff is quiet I think ordinary 90 EP is all you will need to use.

If noisy you can use a heavier oil.

I use Red-line synthetic  diff oil in my LSD (Over $50 per litre) but will be adding LSD additive when I rebuild my 6.9 rear end - it certainly quietens it quite significantly over ordinary oil.

Bill