In my 83 which started life as a 240d but now has a euro na 300d, a five speed od tranny and a 307 diff I get 20 around town and 35 highway. Fresh engine and very nice michelin hydroedge tires too. I drive 75 highway.

A stock 300d na would be lucky to do 25 highway with the 346 gears and automatic.

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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.