Oil pressure gauge started to climb over the right to far

[StockMan]

I have a 68 charger and for years had no issues with all of my functioning gauges.  Over the past summer I started to notice the oil pressure gauge drift a little to far over to the max side.  When pulling up to a stop it would settle down back to 45-50lbs and them climb back up to 62-65 or so on the road.  I put the manual gauge on it and it read the correct pressure.  Again, periodically, it would creep over to the max.  So this week now it started climbing right over past max, and I've seen gauges cook themselves by doing this to I unhooked it.  I bought a new sending unit, ran with that for a short time and all appeared to be good.  the new unit actually had the gauge reporting a more accurate pressure, more in line with my external gauge.  Didn't take long before the problem surfaced again, so I guess it couldn't have been the sending unit.  What would cause this, bad ground? thanks 

[b5blue]

It's the 5V supply on the rear of the cluster. Watch it if it fails completely it could be big trouble. 

[John_Kunkel]

If the Instrument Voltage Regulator (IVR) was the problem, the fuel and temp gauges would climb too. Not unheard of for a replacement sender to go bad.

[Nacho-RT74]

Or the wire being grounded somewhere

[StockMan]

If the Instrument Voltage Regulator (IVR) was the problem, the fuel and temp gauges would climb too. Not unheard of for a replacement sender to go bad.

This is what I was thinking, the other gauges would be reading high was well.  Yeah, I don't want to hook it back up until I figure it out, I've had to rebuild a couple of cook gauges for losing a ground and its just becomes time consuming.