The VIN look up site (https://www.ilcats.ru/mercedes/?vin) gives me 4 options to one VIN. Which is strange since I thought a VIN pertained to a particular car.
2 of the options show it with the 2.24, 2 with the 2.47. What gives?

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'83 SD, 2x '85 SD
You are entitled to your own opinions, you are not entitled to your own facts.

2.47 is for the detuned us version, the 224 is for the more powerful euro version.

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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.

That would seem make sense. The shop manual (German version) shows the 380SEC as having the 2.47 and the 500SEC the 2.24.

Would the 2.47 out of a US 500SEC be a straight swap into a '85 SD with the 2.88?

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'83 SD, 2x '85 SD
You are entitled to your own opinions, you are not entitled to your own facts.

Yes, providing that the half-shafts/axles from the SEC stay with the center section.
The yoke on the input shaft will also have to be swapped for the smaller one to match the SD flex joint.

Just to make sure I understand the terminology:

1. By half-shafts/axles you mean those parts circled in yellow in the photo? So I'll have to take those from the 500SEC and put them in the 300SD?
2. Presumably because the ones on the SD are of the wrong dimensions and won't work with the 2.47 diff?
3. By "center section" you mean the actual diff i.e. "pumpkin"?

4. By "yoke" you mean the part circled in red on the diagram? This is one piece with the rear half of the drive shaft so I'd need the rear half of the drive shaft from the 500SEC?

Attached Thumbnails

   

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'83 SD, 2x '85 SD
You are entitled to your own opinions, you are not entitled to your own facts.

1-3 correct.
4. The yoke referred to is also called the "three-legged flange". It is on the input shaft (pinion shaft) of the differential, not in the drive line.

If anyone is looking for a 2.24 rear end from a 560, I'm pretty sure that I have one laying around with the axles here in North Texas.

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With best regards

Al

I just pulled the wider 2.47 (210mm, 1.3l) differential with annular half shafts from 'Desert Rose' (FKA 'Phil' when owned by Doktor Bert).
The combination will fit a W116 and an early W126.
It has the smaller pinion flange required to fit the 300SD guibo on the tail end of the driveshaft.

Note: the photo is from this February 2014 post:
My new 1978 300SD
Send me a PM if interested.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

Thanks for the confirmation and correction. Nomenclature can be tricky! They do indeed appear to call it a "flange" in the parts catalogue (https://www.ilcats.ru/mercedes)

Attached Thumbnails

 

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'83 SD, 2x '85 SD
You are entitled to your own opinions, you are not entitled to your own facts.

Just to doubly confirm: The half shafts that came with the 2.47 (regardless out of which 126 it came be it SE, SEL or SEC) are needed to make it fit in the 300SD?
Why don't the ones on the 300SD fit, too long, short, or mismatched linkage?

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'83 SD, 2x '85 SD
You are entitled to your own opinions, you are not entitled to your own facts.

WD:

For the chassis R/C107, W114/115, W116, W123, and W126, center pieces (aka diffs) were produced in two sizes: 185mm ring gear (small center piece), and 210mm ring gear (large center piece). The large center piece (which includes the 2.47 ratio), is wider than the small (which includes the 2.88 ratio). Consequently, the axle shafts for the large are shorter than those for the small.

X2 on what Frank Reiner stated.
The wider W126 210 mm differential (center carrier/pumpkin) requires the shorter half axles W126 to fit correctly.
The longer W126 half axles used with the narrower 185 mm differential will be too long to be used with the 210 mm differential.

Note: there are two different styles of half axles.

The annular (bolt on style) half shafts bolt to stub shafts in the differential and their CV joints are very easy to reboot.
No need to remove the differential cover to remove the half axles.
You just remove the bolts connecting the half shaft to the stub shaft.
The annular half shafts and stub shafts are still available new from MB.

The homokinetic (crimped can style) half axles have CV joints that are much more difficult to reboot.
This is due to the need to crimp the replacement metal CV joint can.
The differential also has to be opened to remove the C-clips that hold the half axles in place.
New homokinetic half shafts are NLA from MB.

The photograph of the differential previously installed on 'Desert Rose' shows the bolt on annular style half shafts (with the stub axles).

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022