If you are dropping the voltage, you put the "voltage reducer" in series/inline on the hot wire that goes to the gauge. The one that is only hot when key is on.
Just because your gauge reads wrong does not necessarily mean you have it wired wrong. It could be a few other things.

WHAT TERMINAL: It should have an S for sender and a + for hot. Or it may have a red tag (or what's left of a red tag,) which is the sender terminal. If all else fails, the sender terminal is usually on the FULL side of gauge.


Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn