Oil pressure gauge spikes at 60

Sound,s like you may have a loose ground,or may have shorted out the oil sending unit.

Where would the ground be? The cluster plugs into the dash.

Usually there is a indiviual ground wire,or metal bracket that supplys the ground.

T_S_T The cluster plugs in and is secured by 4 screws. I didn't see a ground wire or bracket

If all other guages, work /fuel temp and alternator and just the oil pressure is not,check the oil sending unit,it is most likely your issue if all others are working right.

T_S_T All other gauges work fine. How did removing the cluster mess up the sending unit...just asking. Also, where is the sending unit?

It shorted it out,if you did not remove battery cable when you done the swap,the sending unit is on side of motor block right above oil pan on driver side.

I did NOT remove the battery cable. I'll change that sending unit Saturday and let you know how it goes. Thank you for your help. Joe White