OK you wiring guru's HELP!!!!!

[Eyegore]

My son is installing the autometer guages, everything is in but the dual fuel tank connection. He has dual tanks everything runs in through conectors under the dash and one red & black wire runs up to the dash cluster, is this the one (red & balck) wire he would connect his gauge to for both tanks?
Unfortunantly we do not have access to a wiring diagram so anyone with one we would certainly appreciate your help.

Thanks


Tom