my gauges specifically the oil and temperature gauges buries the needle once the truck is running. The motor is not even warm and the temperature gauge is buried to H. What may cause this to do it? Could the sending units be bad? It sat without running for almost 2 years. Wiring is all good. Thanks for any ideas.

 

I suspect the wireing.......maybe mouse damage??
Usually a sending unit alone won't peg a gauge.
I belive if it was the Instrument Cluster Voltage Regulator then the fuel gauge would be pegged as well. and they would all be off with or without he engine running.
I also belive if the sending units were bad the gauges would again be pegged engine running or not.

I'd turn the key on and get under the hood and start moving the wire while someone watches the gauges or take a video of it.

 

maybe there is dirt in the connections, like the previous poster said wiggle the connector at the sending unit and see what happens

 

what year is the truck?

Might be the voltage regulator.. Could have stopped regulating.

 

Please, when asking questions, list all the pertinent info: Year, series, engine size and etc.

Your profile says 1968, but which 1968? C series, F series? I need to know, so I can list the part number/applications for the following little charmer:

Bolted to the backside of the instrument cluster is the ICVR = Instrument Cluster Voltage Regulator.

Regulates 'juice" to the oil/temp and fuel gauges. When it begins to fail, the needles of these gauges do the hula, swing wildly back/forth on their own.

When the little charmer fails, the gauge needles peg, and/or lay there like a drunken sailor.