I recently got a blaster gm coil, which works, and a MSD 5 box that I can't get working. The wires all all connected as the instruction manual says and the ground wire is connected to the firewall where one of the engine grounds is. With it all connected like this there is no spark coming from the coil I'm using the 8876 harness by the way Anyone have any idea what I could be doing wrong, and the box is used so I guess it could be broken?

ok, i have an msd 5 box, and looked up online how to wire it, it says that the msd 5 box with an gm hei internal coil is not recromended, i dont know why, but its not, now im lookin in to a msd 6 box, not too cheap, but its supposta work, now with the external coil, wich i think u got, or thats what it sounds like, it woks, just go to the msd site, and open the right file, and youll get dozens of wireing diagrams, including the one you need.