I have a german language owners manual that came with my euro 300d that I parted out. It shows the five speed as an option in the 240d. Remember the euro 240s have a little more power and are lighter. I believe the five speed is the same in all 123s in which case it has a 17 or 18% OD ratio. I believe that you would be fine on level ground in a 240 with the od and even probably on a small hill but on a bit more you would have to go to fourth.....no problemo in my mind.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.