My Dear Benz Brethren,

What are the differences between 300D & 300SD transmissions? I'm buying a 1985 300SD parts car with a bad tranny - but it's maybe too good for a parts car. I have a 1985 300D parts car with a good tranny. I think that I've read that they're the same except for rear of the tranny (but I can't find the post - Argh! ).

Can I make my 300D tranny into a 300SD tranny? Thanks!

Joe Gottschlich
Dayton, OH
1995 E420 (Beloved Spouse's car)
1982 300D (Daughter's)
1981 300SD (mine!)
1985 300D (parts)

not sure....bu the 300D (W123) has a cable driven speedo, the 85 300SD (W126 has an electronic speedo...so the drive on the tranny is different but can possibly be swapped....but until others who know more about the specifics post that will give you a little something to go on. There are likely other issues I am not sure of.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
---------------------
Section 609 MVAC Certified
---------------------
"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

yes. The speedo pickup on the SD is electronic - a prox sensor that reads slots in the parking pawl plate. The pickup is mounted in a smooth bore hole in the trans rear cover. I don't know for sure if the rear covers are the same, but either way it's easy. The mechanical speedo drive runs off the same helical gear that turns the governor and secondary pump. having the cover off should be all you need to understand. Use the best output shaft shims from either trans or buy from dealer(about $1) to get end play right. The output yoke needs either a 12 point, 30mm socket, or a spanner tool which you can make easily out of a short piece of 1-1/4" black pipe.

__________________
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.