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I have replaced the ring gear (135teeth and it matched tjhe one taken off.
I have replaced the starter four times, sometimes with one spacer.
Each time the starter is immediately noisy and only lasts a few weeks.
The teeth on the startes are chewed down along the top in the center part of the toothe..
I've read that some Ford starters come with an 8 tooth starter gear & some have 9 teeth. I'd give Napa a call & see what they can tell you about this. Or (worst case) check with your friendly neighborhood Ford stealer.