Not all rebuilds are created equal. Automatic transmissions are not the simplest things to work on, and MB knowledge is essential. Years ago, I drove truck for a company that rebuilt automatics and supplied parts to other rebuilders. MOST auto-box rebuilds were CRAP. Absolute junk that wouldn't last long at all.
I would trust only the most expert MB mechanic to rebuild an existing tranny. None to be found? Buy a "crate" MB-rebuild from MB. Not much more than rebuilds anyway...
1998 C230 "Black Betty"