I owned a 240d.
Go for the 300 and make sure it has a turbo. Also dont be afraid to push the throttle to the floor as well as hold it. When the engine is in the shifting revs it should sound like a tradational chevy 350 engine roaring vs a cummins diesel engine. Also the 81 and earliers dont have over drive, so 3rd and 4rd gear are about the same. The automatics are known for the shifting rods to get out of adjustment. Lastly, if it wont shut off, its because of a piece of broken vacuum hose to the fuel shut off solonoid.
