I have been wanting to add overdrive to my 75 w150. I'm running a 727 from 1979 right now paired with a magnum 360 from 2001. The truck is using stock wiring from 1978 and a carb intake (so none of the 2001 controls).

I have looked into the overdrive conversions out there from gear vendors and was initially excited but the dollars added up quick so I started wondering if a newer trans like a 47RE would be the way to go instead.

I have also started reading about the A518 - is that my best option?

With some of the Chevys I have seen aftermarket harnesses and control systems to do a swap like this. For the Mopar stuff I'm coming up short. Anyone have any advice/knowledge on the subject or could you point me in the right direction?