On the fuel gauge the post behind the Full mark goes to the tank sender. The hot wire goes to the post under the Empty. You will damage the sender if hooked up backwards. You will not hurt the amp gauge if the wires are backwards, it will just read discharge when charging. On my amp gauge it seems to work backwards of what I expected. The needle moves in the opposite direction of the current flow. The wire from the voltage regulator goes to the post under the discharge side. Yours may not work that way. Hook it up and turn on the ignition and see if it shows a slight discharge- if it does you are good. If it shows charge reverse the wires.

Chuck