I finally got some other problems in my life sorted out and finished my MB diff swap project. I just got in from a 500 mile road trip and really like it. Now it's got really long legs! It may be a bit flat in forth gear from 60 to 70 or so but pulls well from 70 up, and at 60 to pass I punch down to 3rd run it up to near 4000 rpm let it back into 4rth and it pulls great. I was driving like a fiend for hours on a roller coaster road with grades to over 9% and lots of tight corners, and pulled about 36 MPG. (needless to say the hairier driving was not in a very highly populated area)
I don't know it it would work as well on an SD 'cause I think they are heavier than my CD. Also the 2.47 diff didn't just click into place as the 2.47 is 5/8 inch or so lower at the input shaft. So I used washers to space it tipping it upwards a smidge to point the input shaft at the front engine mounts and spaced all other mounts and center support bearing to line things up. Is it a bit slower 0 to 60? It probably is but not so I notice it. Should others run out and do this? Maybe not if you drive slower or want more power at lower speeds. For me,I found the cars power more than enough stock with a nearly useless first gear and didn't like the sound of the high revs at 75 to 80 mph. Now at 75 it is so quiet it is almost spooky. For me it has made the car nearly perfect!
Alberta Luthier

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Thanx,
Alberta Luthier
1983 300CD ('Stinky')155k miles, 2.47 diff, EGR removed, AAZ injectors with 265 nozzles from Sean,and vogtland lowering springs.
1984 300SD ('Old Blue')150k Klicks from Japan originally, came with rear head rests, no sunroof and never had an EGR