Temp Guage issues

My temp guage does not work and I have changed the sending unit but the guage still will not work (nothing happens even when I turn the key on) . I have read the sevice manual but I don't have the test box they say is needed to test the guage. So does anyone have any idea how to test the guage so I can see if it the guage , wiring, or anything else this is all in my 62 Wagon.