[72lb4x4]

The question is why do you want to add a solenoid, or what problem do you think it will solve?

If your starter is currently making the engine turn, you're not adding a ford solenoid for the right reasons.

In any case, this solution is a bandaid to mask or avoid fixing another problem. A better idea would be to actually fix the real problem.

Adding a solenoid doesn't change the operation of the existing solenoid.
Adding another part makes for another part that will eventually need to be replaced.

I think most of the ford solenoid installs that make a difference do so because of the nearby wiring that was replaced, or at least touched, thereby cleaning the contact points.

I'd probably wire it differently than both drawings above if I used one.