Having just completed this task, there should be NO reason to get one for a Slow-maro. (Chebbys still used a coil back then, too, right?) The main supplier of these is Factory Fit in New Jersy. They will sell you exactly the right harness and answer all your questions. As far as I know, the TH400 kickdown wiring should be on the engine harness, but since I have a manual trans I didn't get that particular set of wires with mine. If you order the harness from Factory fit, carefully look at all the contacts that are inserted into the connector housings very carefully. Some might need some final adjusting, as mine did.
