What is this wire?

[TrojanPower]

I have been working on this 1972 C20. Engine is running very well and heat works. Does not have A/C. This wire has been hanging out in the passenger side of the engine bay since I got the truck. Not sure if its supposed to be attached. Looks like it might have something to do with heater as its length seems to match up there? If anyone know where it goes please advise...
1. Should it be hooked up?
2. Where does it connect?

Green wire
Metal bracket attached to wire.

[kwmech]

It's a green one to match your valve cover.





Usually that wire will be attached to your sending unit in left front of the cylinder head, BUT the connector on the end looks suspicious/different. No other wires around?
Is there a switch on the right side of the automatic?

[TrojanPower]

I am not with the truck right now, but do you mean a switch on the steering column? If it attaches to the cylinder head, can you give more detail?

[kwmech]

Down on the right side of the transmission are the pressure ports. Some of the later trucks had a spark control system that would only allow vacuum to the distributor in 3rd gear. (emissions crap) The green may may go to that switch OR it could be routed inadvertantly to the right side when it should be on the left side to the temp sending unit

[Speeding Dakota]

I also have a 72 C20 and the green wire goes to the thermostat on the passenger side of the block