So you have owned the car since new? If not, someone could have done work to the car before you have owned it.
I am just relaying common information on what normally eats up these gears as you have explained it.
The only other recommendation I would have is to get a new matching Aux shaft and distributor gear and see where things go from there. Stock replacement auto store parts should work fine. In addition, many 2.3s have lasted just fine on the OEM ones. Ford still carries these, but I cannot provide the cost of them.
Cheap, Fast, Reliable. You can only pick two.
Kurt 85 SVO