Autozone asked if the cam syncronizer is with or without a step on plug....Does anyone know what that is, and how do I know if I have one??

 

going to buy a camshaft syncronizer for my '01, and Autozone asked if it was with a "step on plug" or with out...??? I haven't got a clue! Can anyone tell me what that is, and how to detemine if I have one????........ thanks.....greg

 

Never heard that term before, sorry