I got rid of MB buzzer(annoying) and installed Olds Silhouette chime type buzzer. Sounds very soft and modern. To mod yours or to disable it completely one must remove buzzer module located behind instrument cluster then open module and using soldering iron solder out buzzer itself. It's a small black box inside module with 1/4" opening on top. After it's out you can solder wires in its place and connect any chime or buzzer or even 12v light bulb since it gives out 12v and buzzer buzzes. Then 12v is off in about 5sec. I don't know if you can get to module simply removing gauge cluster(I think you will be able thought check on that) because I did mine when I was changing evaporator so my dash was all out. Hope it helps.
Good luck
Victor

__________________
1999 ML430 Silver 135k ml
Smoked LED taillights, Alpine in-dash DVD player, 12" sub, Pioneer components, 2 amps, 4200k HIDs, ML55 headlights, 20" rims, mirror LED blinkers

SOLD. 1996 E320 145k ml. Burgundy

SOLD but miss it everyday 1992 500sel Black
Chime buzzer mod,Alpine CD/MP3 player with stock amp,Euro headlights,S600 grill,20" rims, BEST CAR EVER!

SOLD. 1990 300E White
187k ml,smoked tails,Euro headlights,17rims,Intake,12" sub in first aid kit,alarm/autostart,buzzer mod