Some at this site have said that Auto Zone carries a set of larger allen heads for the differential. I believe it includes 12mm, 14mm; 17mm. The 14mm is not sold at Sears, Home Depot, or other such places. I got mine from the Snap-On guy B4 I heard about the Auto Zone option.
It may be overkill, but I change my differential fluid once a year along with the tranny fluid and coolant. Fluids 'n filters keep the beast alive.
1991 300-SEL - Model 126
M103 - SOHC
James Madison - Oppressors can tyrannize only when they achieve a standing army, an enslaved press, and a disarmed populace.
Liberty Firearms Training - After years of trying to regulate California criminals with a never ending stream of gun control laws they have still not given up with the belief that if they make something a crime that criminals will miraculously start obeying the law.