I friend of mine did something similar with a '99 E320 with about 90K miles. He went to a trusted indy we have around and he recommended to buy a re-built with 1 year warranty for 2K + shipping. The indy will pull the old, send back to rebuilders, install rebuilt, and set-up addaptation with proper equipment.

My friend end up paying:

$2,000 for re-built tranny
$300 shipping of re-built tranny
$1,200 indy labor
$300 shipping old tranny
=====
$3,800 + tax = total

After a year, he says his tranny is running as new.

In your case, after 250K, I agree with you, would look for some cheaper solution. Just to let you know that a re-built for $2K may end up being twice that much at the end of the day.

Maybe you should look for newer used one instead.

Anyways, keep us posted.

Rene

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'99 ML320, '00 C280