RE: JR Servos
Yes, any brand of servo can be used with any receiver. But... There are a few wiring and plug issues to deal with. Consult the attached diagram to see what I am saying.
And Exeter is right on the money. NEVER use a servo horn from any brand other than the ones made for your servo. Most manufacturers use a little different tooth count on the shaft and if you use the incorrect arm on your servo you could find it stripping out or slipping in use, which usually leads to the plane coming home in a bag!!
Ken