Lots of great information. It lead me to do more research and these are a few facts I discovered. I think they are accurate. If buying a Hotspark product, it makes a difference if you have a vacuum advanced dist. or a mechanical advance dist. For a 64 Volvo, Pertronix as well as Hotspark, doesn't have a listing for that year, but both suggest certain one MIGHT work with a bosch setup.The coil that has to be used with this setup as well as pertronix has to have at least 3.2 resistance. I do believe the standard coil might not work over the long haul. I was told that if the coil doesn't have this resistance, it MIGHT burn out the electronic ignition. Also, the stock coils positive side is a large wire coming out of the back of the coil. When the starter is engaged, it stays hot. Most other wires in the vehicle might be hot with the ignition on, but they turn off while the starter is being engaged, then comes back on after the car is started. You really have to find a wire that stays on while the starter is being engaged and stays on. So taping into the coil positive wire might be the best and safest way to use a different coil. As I mentioned earlier, I think these facts are correct and will try to update everyone after I install this Hotspark ignitor. It won't be for several weeks, cause I just found that I have to do a major brake rebuilding before I go to the ignition. Thanks again for everyones input.