so by the sounds of things the 1518 and 1520 are both good candidates. is one better suited then the other?
the 1518 is better if you are running 4s. the 1520 is better if you are running 6s. for 5s, both are good.
They say a good mechanic only needs 2 tools - WD40 & Duct tape. If it moves, and its not supposed to, duct tape. If it doesn't move, and its supposed to, WD40.