I'm running MSD's on 5 vehicles. All were bought used at swap meets except one. It is the only one that gave me any problems and I will be sending it in for repair. All the others are still going strong after years of use.
Like chim said, bench test it. Very easy to do. If it tests good, ya better recheck your truck wiring. MSD has excellent customer support via phone or e-mail. They also have wiring diagrams on their website.
Make sure you post up what you figure out so others can learn from this too. GOOD LUCK!
