Its not like that. The 240 is normal to be neutral I believe. The 617 is not externally balanced unless the crank cannot be made neutral at the factory, then it is made to balance with the crank. In at least 6 instances of standard transmission flywheels with 617 and 240 ds all have been neutral but the 617 must be checked after marking the crank before removing the flywheel. I had a 84 280e which was externally balanced.

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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.