67 Barracuda dash wireing
There was no ground originally that I'm aware of. The only "hefty" wire going to a stud is one of the ammeter wires. That is HOT not a ground
These clusters have a bad habit of developing a few problems. After all, how old ARE these girls?
I guess this is a Rallye? dash?
If so, the voltage regulator / limiter for the temp/ fuel/ oil gauge is INSIDE the fuel gauge. It is possible to defeat that and use an external one. Google it
http://rt-eng.com/rte/index.php/RTE_Limiter_Faq
On my 67 (non Rallye) had the following problems
harness connector pins broken or loose repair as necessary. See here
http://www.forabodiesonly.com/mopar/showthread.php?t=234045
On mine (external instrument limiter) the socket fingers were not making contact with the board and I had to solder jumpers across
The gauge stud nuts were loose on a couple. Replace the nuts and loosen/ tighten several times to scrub the board copper clean
Likewise, clean the bulb socket board area, bend the socket fingers and clean, or replace the sockets. Good time to replace the bulbs.