Hy ThreeTree53, what I did to check which of the Autozone resistors is appropriate was I identified what I was working on to the Autozone website, I used a 1956 Chevrolet 3100 pickup, as 12 volts didn't start to be used until 1955, I used 56 just to be sure they were 12 volt. The first two on the list came up as does/will NOT fit your vehicle, the third resistor p/n DR794 DOES fit your vehicle.
As to your coil question, no not all 12 volt coils are created equal, to begin with there are coils that are designed to work without external resistors, also all different outputs are available. If you went into Autozone and told them you would like to purchase an ignition coil to fit a 1956 Chevrolet 1/2 ton (3100) with a six cylinder engine, they would sell you an ignition coil appropriate to replace your original coil, hope that answers your questions.
