A used trans can be had very reasonably, I replaced the one in my 300SD for about $350.

120k is very low miles for a MB trans to fail (unless badly maintained/abused)....mine lasted to 281k!

I'd replace the trans. A nice 380SE is a pretty rare car!

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

When you say replaced, you mean DIY, rebuilt or used?

I agree. My old 1985 380SE had 278K when I sold it with a perfectly shifting transmission and it was not well maintained either.

I live in NYC folks. Not highway driving. We get 20K out of brake pads if we're lucky. Twenty five years of stop and go takes its toll on a tranny.

My mechanic said the tranny cooler failed and dumped the coolant into the transmission fluid. Torque converter seized. Needs new tranny and cooler which is about $3000 with labor. Looks like she's a goner - parts anyone?