I have a 73 Challenger with a 318 engine that has been sitting for some years, maybe like 5. I changed battery drained out fuel, car will turn over but I can't seem to get any spark. It looks like the original ignition was swapped at some point. There is a 4 prong ballast resistor, stock looking coil, and what appears to be a ready to run or HEI type accel distributor in it. With key on I get 12 volts into ballast resister and 10 - 11 volts at the coil positive, when I crank the voltage at the positive goes down to like 6 or so. Not sure where else to go from here, already changed plugs, wires, cap, rotor, coil, and ballast resistor before I started taking voltage readings because they were old, not that expensive to do, and going to need to be changed anyways since the car was sitting so long. I was hoping changing them would give me some spark but no luck. If anyone can help me where to go from here, I'm figuring testing the distributor is next I'm just not sure how to do that. Any help I can get would be greatly appreciated!By the way most of what I have done to this point is the result of trolling the internet and using my rudimentary engine knowledge so please forgive any misinformation I may be giving above. I'm also dreading if I have to change the distributor as I have never attempted that before.