I need some more help with my cluster swap.I went to my local P.A.Part and bought a cluster from a '89 G.T.A.This car had v8 but I do not know if 305 or 350.My car is a v6.Here is my issue.Oil gauge is pegged out past 60psi.Temp gauge reads about 10 degrees to high.Volt meter reads 9volts,but tested at battery shows 14volts.Tach reads 500 at idle.I am using Auto Meter sending units for oil and temp gauges.Any ideas?Here a the numbers on the yellow sticker on the cluster 25087993 2578-003580 8cy

 

You need to run senders from the donor car. If you had idiot lights before, you'd has switches instead of variable resistors, hence the gauge would peg high or low, because its getting an on/off or all-or-nothing signal. If you had gauges before, you can look up replacement senders for your car and the donor vehicle on sites like Rock Auto's and see if the part numbers are different.

The six cyl and 8 cyl tachometers are programmed differently to account for the difference in ignition pulses. It's most likely a resistor or series of resistors on the circuit board in the tach that is different. You can research what needs to be changed, I'm sure it's been done. Easiest would be just to get a v6 tach.

 

The tach has 3 different resistors for 4 cyl., V6 and V8. Just resolder to correct engine size. The sending units I have found sometimes to be different between engine size. Oil pressure gauge V6's are 80psi and V8's are 60psi and sending units are different. Have not had to do on my 3rd gen but on my 2nd gen swapping from light to gauges had to move wires in IP cluster connector.