I'm thinking that the answer is no (electric speedometer in the W126 vs. the mechanical one in the W123), but could I swap over the speedometer parts from the 300SD transmission into the 300D transmission and use it in the 300SD?

Oh, and what about the cruise control? Could I just leave that disconnected for a while?

__________________
"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes

1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod

2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die."

Swap tail shafts

Does that deal with the cruise control issue as well?

__________________
"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes

1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod

2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die."

There is enough difference that I don't find myself using any parts from a W123 except for OM617 related parts on my 300SD. The cruise control seems to be the same. The computer is different, though. Same actuator and same switch. The wiring seems to be the same, too. Perhaps there is a sensor on the W123 as well as the mechanical speedo. If the differential ratio is different, the computer will be different. I believe the computers are calibrated for a certain gear ratio and sensor input. I have yet to meet an actuator unit that did not work with a W126 as well as a W123.

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1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge

My 300d has a sd tran in it and could see a way to swap the reader

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84 300sd 2.47 dif 360k
26 mpg needs lots of love
given to me in pitty

89 civic hatchback auto 140k
33mpgs soon to be low to mid 40's
been in the family since mile 1

85 300d with unknown knock. driven over 30k with knock and still going. sold for $800

I think I'm correct in saying that the "swap the tail ends" myth has been busted by the likes of mach4, rollguy and deliveryvalve.

Have a look for mach4's diesel SL (107) conversion thread - I think there's evidence somewhere in that mega thread.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

x2.

I was about to get a trans from another member to go 126 -> 123 and decided to run it by my local indy Mercedes shop first.

The owner showed me the exploded parts diagrams for both. No way in hades I can see it working, from difference in the shape/footprint of the tail shaft housings alone. I was looking at the swap for a 1980 300td.

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

nope, not TOTALLY busted... a 123turbo auto trans will work in a 126 if the tail shaft and sender ring is swapped. however, it will NOT work the other way around.

this is assuming both trans are the 722.3xx the 2xx and 4xx will not fit parts to the 3xx or each other.

the 123 mechanical sender fits on the 126 output shaft, but there is no provisions for oiling the parts... so only the electronic sender can be swapped...



your 1980 722.2xx trans is totally different from the .3xx in the 126's...

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

So in the context of this thread you are saying yes then?

You could use a 722.315 - remove the tail cone and the mechanical speedometer part and put the tail cone part from the 722.303 in its place.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

That's exactly what I've done on my 617->107 swap, although I used the tail cone from the 722.3 out of the 380SL. I also swapped the yoke in order to keep the SL's larger flex disks and driveshaft. It works perfectly.

__________________
Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

Well it looks like I'll have to read through that thread again!

Confused - that's me...

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

I went back and checked the various threads and i don't think I ever detailed that part. When I replaced the 722.4 with a 722.3 I took the tail cone from the SL's 722.3 and swapped it to the 722.3 of the 300D. This is what gave me the electric speedo and the option to keep the larger yoke.

I considered this fixing a problem not part of the swap. Guess I should have documented it in the thread.

__________________
Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

Do you mean the Bowden setup or something else? I was doing a complete linkage swap to use the Bowden setup on the earlier car.

Actually my '80 has a vacuum-control-only trans -- .117>? if I recall correctly.

When I saw the parts diagrams it was apparent how completely different the shape of the housing is in the tailshaft area. I could see a difference by looking at the pic of the trans I was supposed to get, but for some reason I still thought the other tailshaft housing would bolt up....

__________________


Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

Hey that's fine - at least I'm not loosing my marbles faster than I thought I was!

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!