You'll just have to figure it out as you go. Mopar master cylinders use oversize fitting on them to keep people from installing them wrong. Aftermarket stuff like Wilwood don't do that. If you buy an aluminum master cylinder from Doctor Diff then it will have the correct fittings. The Doctor Diff master will also have the correct brake rod retention o-ring. The Wilwood master most likely won't have a brake rod rentention device.