I have a 440 and want to use a 518 or 618 behind it. Anyone have any info on which unit to use and how to mate it to a big block?

They never made a 518-618 for the b motors, get a 618 from a v-10 pre electronic shift and use a cvx (I think) adapter.

I dont know anything about the 618 but I would use the 518 with an adapter. I forgot the name of the company that makes the adapter but I believe it is "Roberts something"not real sure though.with the 518 you will neet to run two wires to activate the OD. The first needs to be hot with the ignition switch on the second will be a ground through a switch on the dash to activate the OD.

618 is heavier duty, has steel 5 pinion front carrier, 5 pinion OD carrier, more clutches in the OD unit, double wrap L&R band. It only comes in one bellhousing pattern, the v-10 - cummins.

I have seached and searched but can't a company that makes a bellhousing adapter to mate it up to a big block. Does anyone know the name of a company that makes the adapter?

JVX is the name of one of the companies that makes adapters, better get the ky jelly out!