Ignition issues...

Hi guys! So my 73 dart has started running pretty crap tacular again. I believe the original 5 pin ignition module is going out. If you touch the transistor on it it shocks you which doesn't seem right. So I bought a new aftermarket 4 pin module and the car won't run with it. Took that one back and exchanged it and it still won't run. I did notice that when I turn the key off it will backfire. If I put the old one back on it will run but still crappy. Isn't the four pin supposed to work on a 5 pin harness?