Holy resurected thread batman,

The yolk can be swapped off the tranny or the diff, yes its bolt on, you need a 30mm 12 point long shaft socket, (not the most common item).

The stock axels should work just fine.

I also had a longbody W126 with a 617 turbo, and a 2.47 rear and it was great, averaged 28 MPG over 60K miles, got as high as 31 mpg on some tanks.

AFAIK there is no W123 speedo that will work correctly with the 2.47 diff.

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1984 Euro 300SDC, (4spd standard)
1986 Toyota Landcruiser Diesel HJ60 5spd X2

Gone but not forgotten (some sold, some stripped)
1983 300 SD, 1985 300 SD, 1983 240D, 1986 300 SDL, 1985 300 SDL, 1983 300 D, 1984 300 D, 1985 300SD, 1987 300 SDL, 1983 300 SD, 1985 300 TD Euro, 1983 380SEC, 1990 300 D, 1987 300D, 1982 300D, 1982 300D, 1994 E420, 1987 300 TD, 1987 300 D, 1984 300 D

I'd like to see before and after 0-60 runs to see whats lost.

If its under a second its probably worth the trade off, more than that ehhh not so sure.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

I wish i had done a zero to 60 test on my converted 85 sdl, It was way faster than my 85 300 sd, and 83 300 sd that i have had since. I also never touched the alda, but i had some black smoke, I dont think you actually give up much if anything.

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1984 Euro 300SDC, (4spd standard)
1986 Toyota Landcruiser Diesel HJ60 5spd X2

Gone but not forgotten (some sold, some stripped)
1983 300 SD, 1985 300 SD, 1983 240D, 1986 300 SDL, 1985 300 SDL, 1983 300 D, 1984 300 D, 1985 300SD, 1987 300 SDL, 1983 300 SD, 1985 300 TD Euro, 1983 380SEC, 1990 300 D, 1987 300D, 1982 300D, 1982 300D, 1994 E420, 1987 300 TD, 1987 300 D, 1984 300 D

The only way you don't give up acceleration is if (and this only MIGHT be true) is if the car runs to 60 and in the process skips a shift with the higher ratio in the rear and that makes the difference...IE if with the 307 it shifts to third right before you reach 60 and right after with the taller rear end.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Good point, you just might be onto something with the SDL's. 2-3 shift is at 50.

I'm half tempted to try a 560 rear end to get limited slip and slightly better fuel mileage.

90% of my driving is around town so I probably wouldn't see a big benifit.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Do you still have one? If so can you run a 0-60 and post the numbers?

We know about what a stock one should do.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

I converted my 300SD to the 2.47 differential. 0-60 time increased by 1-2 seconds and fuel economy only increased slightly. Around town, under 50 mph, I had to leave the transmission in 3 otherwise the engine would bog.

If you convert, you won't find that your mpg increase is significant.

Ahh than its not worth it for me, more so because I'd have to keep it in 3rd all the time.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

I cannot see how it would need to be manually kept in third. If the car doesn't shift down by itself it doesn't need to be in third. A diesel is a torque motor, you about cannot bog them down.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Because you want it to be at 1,500-2k around town. If it was at like 1k that would suck you would have to downshift for everything, which is a PITA with these old gear box's.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

no i sold the motor and trans, and scrapped the 85 sel, it was not really worth fixing anyway,

I will post the 0-60 with my Diesel SEC in a few days, the next time my buddy comes over with his 1982 300 SDL (380SEL converted to diesel), ill do a 0-60 test in that car.

Also i didnt have any trouble round town, I used the car for delivering pizzas, It didnt bog, I would have sworn the car was made that way, When i purchased later an 85 300 Sd, with the 2.88 I wanted a 2.47.

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1984 Euro 300SDC, (4spd standard)
1986 Toyota Landcruiser Diesel HJ60 5spd X2

Gone but not forgotten (some sold, some stripped)
1983 300 SD, 1985 300 SD, 1983 240D, 1986 300 SDL, 1985 300 SDL, 1983 300 D, 1984 300 D, 1985 300SD, 1987 300 SDL, 1983 300 SD, 1985 300 TD Euro, 1983 380SEC, 1990 300 D, 1987 300D, 1982 300D, 1982 300D, 1994 E420, 1987 300 TD, 1987 300 D, 1984 300 D

Im contemplating something like this for my 87 300D but havent begun to research which ones have what ratios yet. More so to gain a bit for autocrossing but not too restrictive since the car is a daily driver as well.

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350

looking for a good diff for the above mentioned car. Wondering which MB had the same ratio/size or coming close. Some info would be greatly appreciated.

I used to do a lot more freeway driving but now its mostly city and 55-60....so I don't need to swap anymore. I usually only go 72 on the freeway anyways, and its 3100rpm....doesn't bother me that much. Still not as bad as the Rav4...its a 5 speed (overdrive) and it still runs 3300 at 70mph....and 3650 at 75! Its LOUD. I hate that thing....someday it will be gone....

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Here is the mileage chart for every tank of gas I put in my 1984 300SD. Does anyone want to guess the date I changed the differential from 3.07 to 2.47?

http://www.peachparts.com/shopforum/attachments/diesel-discussion/46878d1186769821-regearing-300sd-differential-mileage.jpg