1975 did use the external coil. I converted mine over to an external coil, from an internal one. You probably already know, but you'll also need: New wires, cap, rotor, coil, remove the resistor wire or ballast resistor, I also can't remeber if the vacuum advance and ignition module comes with the rebuilt dizzy. If not, you'll need those too. I think that's about it. Good luck. John


1968 Chevy C-10, 250 and 3 speed on floor, Hedman headers, Offy intake, Edelbrock 600cfm 4 barrel, HEI
1966 Chevy C-10, motor and tranny went into the '68. Waiting to be restored.