Got an 86 base firebird with v6.Insterment panel is full of light warnings insted of gauges.will a TA or formula cluster go into my dash?also will I have to change the harness or just conectors

 

You may need to swap in the yellow speed sensor decoder box (to the back of the ECM bracket) as per the tech article and go from there. You current speedo is cable driven. I'll look up the wiring connectors in a bit, but I think mostly what you would need to do is to swap over the clusters, install the VSS box and parts, swap over the odometer into the electric speedo, and put in all new gauge senders in place of the idiot light switches (switches are on and off and won't work the gauges at all except the fuel and volts gauges). You will also need to get a V6 tachometer unless you like having the tach read wrong...

 

I've got most everything out of my sons 90 dead bird.but this is a 86.what are the chances of a ta cluster working?From same year.think they had 120mph cluster

 

The same deal as above. The 90 used the sensor buffer integral to the ECM and an electronic speedo head. The cluster in the 86 may or may not have the electronic speedo head. If it doesn't, you will need to swap the speed sensor into the tail of the trans from the 90 in place of the speedo cable adapter but using the gear that was on the speedo shaft (to keep the speedo reading right). Then you can wire up the cluster using the proper wires from the ECM. I think you would want to connect into the brown wire coming off of the back of the speedo head (that runs to the ECM), but don't hold me to it.

If the 86 is already electronic, you would need to retain the buffer box at the back of the factory ECM bracket and wire the VSS wires to the ECM to the buffer VSS wires backwards (yellow to purple and purple to yellow). You won't need to replace the $40 VSS if you do this.