It's tricky to diagnose sounds over the computer, I hope this turns out to be a simple thing .

In general if the noise stops when you depress the clutch it's a tranny issue .

*general* .

Don't forget the magnet ! .

If you have to jamb the center mount in it's wrong, maybe your two side mounts are collapsing .

I just had to replace both in my '82 240D and they were factory mounts, maybe four years old and _never_ allowed to touch oil .

They just settled a bit .

There's a LOT of adjustment in the center mount .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Think you may be confusing the T-mount with the center mount.

The center mount screws directly into the transmission. It’s then held to the cross member by two 13mm bolts. Nothing in the way of adjustment.

The T-mount (flimsy rubber thing from the oil pan) has a page in the FSM about adjusting.

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1981 240D 4sp manual. Ivory White.