Wouldn't you need to place them 180 degrees apart and facing the same direction with respect to the orientation marks to get identical balancing? ....or perhaps placing them face to face is the same thing.....I am not sure.

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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.