Amp gauge issue

[DoubleE]

Newbie to the site. Have recently sold my 62 SS and purchased a 72 C10 short box. My new ride has the full gauge instrument cluster which I suspect one of the previous user's installed. Everything works but the amp (battery) gauge. I have read some older posts here on the subject and understand the basic operation as it's applied to the C10. One thing not mentioned is if the wiring harness along with the gauge cluster needed to be swapped out for this to work.

I was very surprised to see the differences in the pin-out between the idiot light vs the full gauge clusters. I have not torn into this yet but wanted to do some research ahead of time.

Reading thru the old posts seems like they were side tracked on what is a volt mete vs an amp meter is. A couple of poster's were on the right track but should have made the point that ALL electrical meters are based on the D'Arsonval meter movement. Both the Amp meter and Voltmeter are D'Arsonval meter movements that are modified for their specific application using shunt circuits and how they are connected to the circuit configuration being measured.

Eric