high or low starter
sounds more like one set is for a high torque mini starter, and the other is for a factory very large starter
the mini starters can be had at most junkyards off dakota/rams/ram vans from about 1989 on with v6 and v8 engines, for usually $15 there about 20lbs lighter and spin the engine quicker with less battery power
I'd upgrade the starter first, then you don't have to worry about if the headers will fit