First - don't use the started until it is fixed because the flywheel replacement is a LOT of work.
From past posts:
I put in a ten tooth gear and everything was fine except that I also replaced the solenoid with the 'best' that O'Rielly has. The made in China solenoid stuck once; a junk-yard genuine Ford part is better. (Rangers have an ‘old’ style solenoid)
I have a new fly-wheel and original 9-tooth starter and fine. All flywheels are now made in China – the one from Autozone had to be junked, this on from Rock Auto has been in for about 30,000 mile so far.
FYI: The starter can only go on one way and the clearance is determined by the rear engine plate and when I bolted it to the transmission bell-housing, it didn't make more than a couple thousandths of difference. Some Fords could use a flywheel shim, but not these Rangers. Look at the way it works and you will see why.
Auto and stick starters are the same from the parts stores. If there is a difference from the factory, it would be slight if any. I held an auto and a stick starter-drive together and didn't see and difference - but I didn't use a micrometer to see if there were any measurable differences.
An escort starter gear (10 teeth) got me through until I had to swap transmissions and a new flywheel so that escort gear is something to look at.
The Ford starters of this style last a very longtime. I only needed two or three in a Pinto (same starter as the Ranger) that ran 240,000 miles mostly for deliveries in San Francisco with lots of starts and stops.
The original flywheel and starter were on the truck when I bought it and were probably ten years old. In my experience, Ford starters last a very long time---
I also ran a 10 gage ground wire from one of the starter bolts to the frame and that seemed to help with the power to the starter.
ALSO - I had problems with Autozone and they wouldn't give my money back on a bad starter - Another guy here said they will. If you do take it back, they want the receipt from the OTHER place that you buy from - at least that's what they told me in Sacramento, CA - so I just tossed it and counted it as a lesson.