I faced th same dilema with my 1989 a year ago. The car had 235k on it.Should I fix it or trade it?
I decided to throw $3,800. in repair on it. Valve guides,/ job, suspension work, shocks, bushings, full tune up, new battery, new rubber hoses & belts, new radiator, new exhaust system, all fluids, flex-disks, etc. etc.
it is the best car investment I could do.
Compare that to the price of a new/used car.
I'm still driving the MB, drives, and runs like the day I bought it in 1993.
For that price, I would have ended-up in a 5 year old ricer. No comparision.