Sounds like a bad starter gear. You could try turning the crank pulley 90 degrees and see if the starter engages after that. It could also be the flywheel teeth are messed up, but more likely it's the starter gear.

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1998 Ranger Supercab 4.0L, Medium Metallic XLT, auto, painted valve covers (10 HP), 30x9.5/15.

2008 Mustang GT, stroked 5.0 3v, RGR cams, R2300 S/C, suspension, Kooks LTs w/HF cats GT500 TB, Flowmaster cat-back exhaust, GT500 fuel pump setup.