i went to buy a new coil for my 68 amx 390 automatic and when they brought it out , on the side of the coil it said to use with an external resistor ?? i have never seen a resistor on this car does it have one ?? i traced the wire from the coil and it goes into the firewall and no resistor in site ?? is it under the dash ?? i thought it took just a plain 12volt coil .. i didn`t want to buy the wrong item so i`m double checking .. can someone clear this up thanx ..