I am trying to get all the electrics in my 71 to work and I am kind of stuck at the fuel and amp gauge, how can I test these without having to rewire my system?

I'm no electrical guru or anything, but personally I'd use a voltmeter to test continuity in the circuit system first.

Someone posted this a long time ago.
Fuel Gauge:
Looking at the back of the gauge as it is mounted in the dash.
1st. The stud at 3 o'clock should be connected to +12V
2nd. The stud at 6 o'clock should be connected to GND. Watch the needle, it should move to a point past the "F" and stop.
3rd. The stud at 9 o'clock should be connected to GND, also. Watch the needle, it should move slowly to the "E".
If the needle moves as described above the guage is OK.
(This does not test the sending unit and/or accuracy of the gauge)

Thanx for the help, I will check the gauge as soon as I get a chance!