The original question missed one point, what is the length of the cable you have? Per the 75 Ford Car Parts (aka MPC), there was a change in length of the battery ground cable on 10/06/69 from 42 inches to 44 inches for what looks like all engines. Which brings up another question, what engine are you trying to wire up? Get in the habit of listing your VIN, at least up to the last two numbers (use "xx" for the last two). The VIN gives up plant, body type, engine and approximate build date. It could make a difference.
Jim