3800 at 80mph in a 3.07 with stock wheels sounds pretty close, the tach might be off a bit. I usually run around 3400 at 75mph in our '82 300SD's.

My 420sel with a 2.47 diff is about 2950rpm at 80....so 3700ish is about right for a 3.07.

The 85's have a 2.88 differential which does drop a few hundred rpm off and helps a bit.

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