Just to clarify. The numbers 85 and 84 in the list above represent years 1985 and 1984 correct?

Yes..,

When considering a rear end swap one has to also consider the tranny ratios. Did MB change ratios of the automatics between cars in the same class (W123 for example) Did they change them much between models with same engine (W123 vs W126)

Sorry I know I should know some of this. Im still trying to stuff all this into my head. If someone has a list of trannies I will try to find time to make a spread sheet file with rear end and tranny's listed together if folk think it would help.

So it was a 380SE diff. That makes sense. I had a 300SE and it felt like the engine would hit redline before 100mph. The dragstrip crowd will pay plenty for a 300SE diff :)

Sixto
95 S420
87 300SDL

Well it seems it was a 380 SE then. The swap was very simple. Pulled the old one out, switched the input yoke with the smaller SD one, bolted everything back in and dropped in the 160 MPH speedo. Nothing more to it.

Oh and just so you know my old rear end was that of the 80 300SD, according to the chart 3.07. No wonder she feels a bit different....

How have your 0-60 times changed?

I have not yet checked 0-60 but I will post results soon.

Where did you find the rear end ratios? I have an '84 230e clunker that I would use as a rear end donor for my 300d if I thought it would make a difference, but I don't see the 230 listed. I think the car originally came from Canada, not the US. How can I find out the rear end ratio?
-andy

I found a whole bunch of rear axle ratios in the 123 and 126 model CD's. I'd scan and post but it would probably take four separate posts.

adsitco.com

Here, click here!

Actually, the 230E has the same differential as the 240D. A 3.69! That old 4-banger must be pushing the revs out, huh?

Thanks for the adsitco post. A lot easier to understand than the MB Manuals.

I don't care how cold or how much snow there is, I'm hitting the junk yard this weekend!

Here's another link to an online calculator of tire size:

http://www.miata.net/garage/tirecalc.html

Take the height of the proper tire and plug it in, and figure out MPH with the different differentials at certain RPM, go to

http://www.prestage.com/Car+Math/Gear+Ratios+and+Tire+Sizes+/Calculate+MPH/default.aspx to figure it out. Very simple to use.

Its very accurate...:)