hi . i was told about a car for sale for 500. it runs very well. the only apparent problem that it has is it doesnt shift into reverse(auto trans) could this be a simple problem, or could it need a new tranny ? any info would be appreciated. thanks its a 300 series.

turms out the car is a 1981 300d. any advice on the trany ?

Figure $2,500-$2,800 for a rebuilt tranny in your negotiations. Thay may exceed the value of the car depending on the condition and mileage. There are alot of good W123's out there.