[gsharapa]

Don't use the harness except for the tach lead, ground wire and hot ignition wire.

Wire it per the MSD instructions, which takes two wires to the coil and two wires to the distributor. Ground the box to the ground wire and take the hot big red positive lead to the solinoid. Tach to the plug in on the box and ignition wire to the one coming from your ingition switch.

I've done two SPF Cobras this way and the dealers do it also!

Note: Make sure you change the coil to the MSD Blaster as the MSD box will burn up the stock coil. Flat spot at 4,300 I might be looking at the vacume 750 carb. Is it leaning out? That 392 stroker want lots of fuel and I use to run a 750 double pumper on a 385 HP 351. Something to think about. How is it jetted?