Large RED wire, directly to the battery positive terminal, not the solenoid or terminal block, directly to the battery. Large BLACK wire, directly to the battery negative terminal, not to frame ground, or other ground, direct to the battery. Small RED power-up wire, to the existing coil power-up wire(s), as the MSD will read from 7 to 16 volts for this wire. If you must 12 volt the small RED wire, from lack of confidence in the electrical system, look on the fuse box, for a terminal marked IGN or IGNITION. Check this terminal for voltage in both ignition switch positions run and start. Voltage present in BOTH positions, cold in all other ignition switch positions, wire the MSD red wire to that terminal, but no other power takeoff to that terminal, only the MSD power-up feed wire.
I never have. Usually, what kills an MSD unit is their RED Blaster II coils made in Mexico (layer shorting), so don't use them.
Mark, I know Dave recommends the Acell 8140 coil or the MSD 8200 chrome coil. (both made in good ol USA) I used the 8140 and it failed with my MSD digital 6 ignition. Dave said it was a fluke and he's never had a problem with them. I then bought the MSD 8200, and haven't had a problem since. BTW, According to my MSD manual, the box has it's own protection against shorts and such, no fuse needed.
