[FirstOwner69]

First, welcome to the forum!

Second, I'm no expert on wiring, but I'll try to answer some of your questions.

- I wouldn't give up on the gauges until you replace the printed circuit and get everything else in good order.

- The battery gauge is not a volt meter. It's an ammeter that should normally be slightly to the right or left of center. Left is discharging. Right is charging. The needle position doesn't vary much. If it's not working at all, there is a fuse holder near each headlight. Each fuse holder contains a short 4 amp fuse (fuse holder is shown at the top of the picture below). One or both fuses may be blown.

- The soldered wires (shown at the bottom of the picture below) are part of the factory harness.

- The factory temperature gauge is fed by a dark green wire that connects to a sending unit on the engine. I don't know where the sender is on an I6. On a small block it's in the left head. It's possible that the aftermarket gauge is utilizing this wire but probably not the factory sending unit. However, the aftermarket sending unit may be in the factory location. Obviously, the factory gauge would not work in this scenario.

- I've never heard of a parking brake warning light in these trucks. There is a warning light which warns of a malfunction in the hydraulic brake system. It's fed by a tan wire that attaches to the brake proportioning valve on 71s/72s or distribution block on 67s-70s and runs to the cluster plug which feeds the brake light on the fuel gauge via the printed circuit.

- I don't know what you mean by the "the speedo gets wirey when on the highway". The speedo is mechanical and is driven by a cable to the transmission. It will bounce if it needs lubrication or if it's kinked. Back in the day they recommended powered graphite for lubrication.