Im on this website the other day and Im looking at the various transmissions for the different Merc models. WOW, a lotta different trannys out there...my question is: I have heard from a few different mechanics that a few of the different model trannys will work with my engine. However, I have heard from a few mechanics that say that only the 722.321 will work with my 603 engine.

I have an 86' 300SDL with the 722.321 tranny and a 603 engine...the 722.321 was for both 86-87 models of 300SDL...who is right? Can I take a tranny OTHER than the 722.321 and make it work with my 603?

Some on this forum have replaced their trannys with a 240D with success...but I dont feel like tackling a manual overhaul.

So all you Mercedes mechanics out there...what do you think? Can any other auto transmission work with my 300SDL if I need to replace it?

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"Cool Blue"

The 86-87 SDL parts cars aren't so rare that you should take a chance with anything else unless you have a severly limited budget.

Staying within the Diesel family, you can't use a 124 transmission because the 126 uses an inductive speedo drive vs the 124's mechanical drive. My guess is the 201 uses a mechanical drive as well but I don't know for sure. And 201 transmission into a 126 doesn't sound right. That leaves the 90-91 350SD/L and 140 Diesels as the most likely donors. 617 transmissions have a different bolt pattern.

IIRC the M103 and M104 have nearly identical block interfaces to the 603 so there are lots of gasser transmissions to experiment with. If that works, I'd like to try a 722.5 5-speed AT behind a 603 if it'll fit a 124 transmission hump.

Sixto
87 300D

For your 86foot (you said 86' didn't you?) SDL, the transmission is unique. The '90/'91 SD & SDL have a different model.

The differences likely have more to do with the radically different power curve and reduced RPM range of the 3.5L engine than anything else.

The differences between many of these transmissions is in the valve body and in the torque converter, the gearing and clutches less so.

As Sixto mentioned, the tailpiece of the 126 has the speed output for the speedometer, the 201 and 124 are mechanical drives. The mechanical drive can be adapted to a short cable or adapter with an electronic speedo drive on it, ... if you know what the output needs to be. That would probably be much easier than tearing into the transmission to replace the gear-drive with a reluctor-type output.

I can't see where any 617/616 engine's transmissions can be made to work, I understand that the starter is on the wrong side for 60x application.

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Gone to the dark side

- Jeff

Its not so much a budget issue for me as is the area I live in...not a whole lotta scrap yards with old mercs. I looked through one today and all I found was an old 240D...the engine and tranny were still intact but she hadnt been moved in a while.

At least I had an explanation as to why or why not my merc would take a different tranny...does anyone know of someone who has put a 722.5 manual into a 603? That would be something I would be very keen on seeing!

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"Cool Blue"

722.5 is a 5-speed automatic.

The 5-speed MT from a 190E or 300E should bolt up to your engine. More difficult is finding a clutch pedal and master cylinder from a Euro 126. I don't know if the 603 crank has to be drilled to take a pilot bearing.

Sixto
87 300D