Rallye Instrument cluster voltage limiter - 68 Barracuda

No idea why your FSM doesn't have the Rally cluster. I'm pretty sure the Plymouth '68 FSM does. The '67 does not. Dodge '68 I don't know.

I'm referencing the Barracuda instrument panel wiring diagram in the 68 Plymouth service manual (8-112 & 8-113), where it didn't show a voltage limiter while the Valiant wiring diagram does. That was the source of my confusion. Now knowing it's internal to the fuel gauge explains that.

Thanks for the help, I'll read through these links.