Greg, look into how an MSD box is wired into a Ford Duraspark system. You might find your answers here.
MSD has the schematics for a few different wiring methods.
1) MSD box all on its own, wired outside the factory wiring harness.
2) MSD box all on its own but grafted into the factory wiring harness. (Using the factory Duraspark plugs and wires)
3) MSD box wired in conjunction with the factory Duraspark system, effectively giving the option to run either system should one system fail... like a backup system.

The early MSD box users often ran both systems because they thought having the backup (Duraspark) was a good idea should the MSD box fail.

Does the truck have a factory tach?.. Or did it have an aftermarket Tach?
Sometimes people tried weird things to get the tach to work with the MSD box and ended up with a big problem after butchering the harness attempting different things.

Ya know it can’t be said enough. Some of the people you meet at the track especially the reunion are some real good people.
It’s always great when you go racing and come back in one piece.

My friend bought a 78 F-150 4WD 351M short bed off a farmers estate. Has not run in 10 years.
We got it running but it runs like crap, a good reason to park it.
I was trying to perk it up a little and the spark was real week, I mean I was surprised it would fire up and run like that.
Went to install a new module and the previous owner had made some change's.
He had cut off the red wire and capped it with a wire cap on the 2 wire plug and had the white wire connected.
I don't know much about the dura spark system, but what would be the reason to cut the red wire?
Any help will get you a free beer if you want to come to Oklahoma and collect.
Greg

Powell Machine explains why

     Sorta lacks from the empirical evidence standpoint leading to any 'real' conclusions; but then, what do you expect from a u-tube video.   

     Scott.

Well good for you. Hate the deal went sideways. I saw it live when you first posted it , but didnt check back until it was over. I do not really watch BAT. Always seems it is the new BJ as far as prices so sort of puts me out .