Starter will just spin and will turn the motor

Hi and thanks for using 2CarPros.

Based on your description, either the Bendix isn't engaging the starter and flywheel, which is unlikely if it is doing the same thing as the old starter, or there are problems with the teeth on the flywheel allowing the starter to spin without engagement.

What I suggest is to disconnect the battery and remove the starter. First, inspect the flywheel from where the starter is placed. See if the teeth or gears are damaged on the flywheel not giving the starter a place to engage. If they are good, bench test the starter to confirm the Bendix kicks out when the starter is powered. If it doesn't, you got a bad starter.

Let me know what you find or if you have other questions.

Joe