87 Insturment cluster into an 84

[skilsmoov]

I would like to change my instrument cluster from the dummy light to a guage cluster. I am also planning on getting the a/c system  as well. Would I need to get the wiring harness from the 87 to make the instrument cluster and a/c unit work? I have done searches but keep coming up empty. Thanks for any help!!

[VileZambonie]

That would be the easiest thing to do is swap everything.

[skilsmoov]

Well I have replaced the whole wiring harness, but I'm having some problems.  Hoping someone can help. When I switch the key the fuel gauge went over pass full, and the oil pressure gauge goes to 60. I think there maybe should be a ground, but Im not sure where it should be. Now let me tell you that truck I got the harness out of had two tanks. Mine only has one. Everything is hooked up and in place with exception of a few wires, and I am hoping someone can help me figure out where they are suppose to go. The first picture is of the gauge, and the second picture is of the four wires that come of the speedo thing. And there is a plug with a Orange and White wires I dont know what this is suppose to plug into. Please help! I have been looking at the wiring diagrams and have found most everything, but I'm stumped on these problems.

[Captkaos]

Did you repin the harness or at least check them to make sure everything was in the right place.