Alright need a little input. I picked up a early 70's 400 out of a truck that had a 4 speed behind it. Got to lookin at some stuff and it seems as if someone (factory??) has balanced everything. Dont know if the internals were done but the balancer looks like its been balanced and so does the flywheel that came with it. The balancer has a few shallow drill holes in it and the flywheel has been shaved on one side in a spot or two. Well Im runnin an automatic, my question is should I use a stock cast crank converter or an aftermarket one with the original balancer??? And I have read that the 4 speed truck had these parts but not sure how extensive it is.