88 s10 radio

Hi all, I'm simply trying to swap out a factory am/fm tape deck for the old factory am dial radio in my s10 pickup. It's a 1988 with a 4 cylinder and just wanted the fm is all. Picked up a factory radio but when i plugged it in the display won't work and i just get static coming through. My power plug only has three wires and is missing BROWN / orange and I'm wondering if this is the problem. Any help would be appreciated.

Yes that is your problem.  Your dial radio does not need a constant wire to keep memory.  The Orange wire is the memory wire.  You need to connect this wire to the orange wire that is connected to the cigarette lighter.  If you have no cigarette lighter, you will need to connect it to a constant 12 volt source.

Thanks all, that's exactly what it was, constant power was all I needed.