Opinions vary as to source on those parts. Fender is not terribly picky. Could be Gotoh, Schaller or Ping. You probably won't find Ping parts anywhere - they're more an OEM for everybody else. Doesn't matter - you already have them. So, what you really need is a tool known as a "caliper".
You can measure inside and outside lengths and diameters as well as depths to within .001" and you'd have to work pretty hard to spend more than $20 on one. Excellent tool to have. Answers a lotta questions.
Once you know the dimensions of your hardware and/or mounting points, it gets a lot easier to select/replace it.
The vast majority of these things will flip between SAE and Metric measurements at the press of a button, too. Pretty handy. You can even measure string gauges with them.