I found this in my Mercedes Tech Data manual edition Jan 1981. Not sure if model 123.193 is the correct model of the transmission in my 83 300DT but it's looks like the closest one I was able to find in the manual which shows a model 123.193 as a 300 TD Turbodiesel with a 617.952 engine. Now, a TD is a wagon but mine is a sedan which makes it a DT. Maybe it's close enough for determining shift points in my 83 DT transmission?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

For those of us that aren't skilled sideways readers

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Thanks....I even was trying to read it sideways!!!