I finally got a complete answer from another Mercedes list:

As my source I am quoting (with minor edits) from:

1993 Sales Brochure - The 300 Class,
MB Pulbication MC-92-103-200

"The Automatic Locking Differential (ASD) operates automatically at speeds
below 19mph to limit wheel slip. ASD is a computer controlled, variable,
hydraulic-locking differential which redistributes power away from the
slipping rear wheel.... ASD is available on the 300D 2.5 Turbo Sedan."

"The Automatic Slip Control (ASR) system uses both throttle and brake
control to reduce whell spin during aceleration. Below 24mph, if wheel
slippage is detected, the brakes are applied to either or both rear wehels.
If wheel slippage continues, the engine is then automatically throttled
badck until traction returns. Above 24mph, the engine is throttled back
before the brakes are applied. ASR is available on all 300 Class vehicles
except the 300D 2.5 Turbo and 4matic models, and is standard on the 500E"

Hope this helps,

Kevin Kenner
Seattle, Washington

:-) neil
1988 360TE AMG
1993 500E