New starter

Alright, so got my 73 dart 225 4 door fully road worthy. ie: got all exterior lights working, and the car can stop now which is a plus. engine and Trans are in great shape, but every time I turn the key, the starter sounds like a gravel tumbler. So here's where I'm at, I'm looking to replace the starter, but from what I understand new starters are mini. are there any major complications, other parts I need to replace at the same time? pretend like I don't know anything, and give me what you got.

Thanks as always.