All the W140 gassers had optional ASR, which is electronic traction control. Some models have this standard. Look for a yellow/orange warning triangle in the middle of the speedometer. These cars have an open diff, but simulate limited-slip via electronics.
The W140 diesel had optional ASD, which is limited-slip plus a hydrualic lockup function. Totally different system than ASR. So to answer your question, yes, I believe it was an option, and it's called ASR... and you can tell by obtaining a photo of the speedometer.
