I did the B1 o-ring without lowering the tranny or removing the exhaust. Link and info here. The part number is for a 300SDL 722.321 but it may be the same. I would rate it 7 on a scale of 1-10 in difficulties. You have to be very patient. You need to make some kind of a tool as the spring is very strong and no way you can push it back in by hand. I think MBZ has a tool for it with the tranny on the bench. So it is very hard when you are on your back side, if you do not have a lift.

Good luck.

http://www.peachparts.com/shopforum/diesel-discussion/324822-300sdl-tranny-leak-here-picture.html

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.