I have an 87 trans am that im working on eliminating the computer, I already have everything with the engine done. now I have to rewire all the gauges, can the stock gauges be rewired to work without the computer? has anyone done this before and know how to do it? Im not really sure on how to wire the gauges.

OK, i don't have my book on me... but i also have an 86 that was converted to a Natural asperated carb.... and i was looking at this last night... so again i might be wrong. (i'm not original owner, so this wiring sucks **** on mine)

Speedometer: - Mine is cable, easy, no wires.
Tach: This is a brown wire from your Distributor, into firewall, to gauge.
Battery: This is just a volt meter, Hot and ground on gauge.
Fuel gauge: (mine doesnt work yet, so this is theory) if your running your in-tank fuel pump (i'm not) there is a pink wire that runns from your back seats to your gauge and should be like 0-90ohms... if your converting over, you shouldn't need to touch it... should still work.
Oil Pressure: ----I dunno... in fact, i can't figure mine out. I think i got a large copper tube(?) running to my aftermarket gauge. But I think that runs from back by your Distributor (on block though) through firewall, to gauge. could be wrong though

It turns out only the speedo is controlled by the computer, I got all the other gauges working, what do I have to do to make the speedo work without the computer?

Well, the speedometer needs to see a buffered signal. Now I'm not sure which way the signal goes, but it's probably either one of two ways. A/C signal created from the VSS is sent to the ECM, and ECM reads it as speed, and then sends a buffered signal to the gauge OR the ECM sends the VSS signal, and it is buffered AT the back of the speedometer by a little yellow box. Without the ECM in the car, you have broken the link between the VSS and the speedometer. Realistically, you could just take the VSS wires and run them directly to the signal input of the speedometer(more than likely that yellow box) and it should read. I might be wrong, though, and if I am hopefully someone else can chime in.

The speedo is not computer controlled in any thirdgen. Electronic speedometers use the VSS signal directly independently of the ECM.