97 GMC Factory wiring?

[70GMCer]

When I bought this truck over a year ago, someone had installed a single din Kenwood head unit into the double din opening with a kit.

I want to replace it with an original factory radio. I'm not into all that fancy sound. Just want it back to stock.

My question is, looking at the picture, the harness coming from the inside of the dash, does the plug directly into the original radio? Or do I need another harness to the original factory radio?

It looks like who ever installed the newer head unit had a kit with a plug that plugged into the original harness. I'm I right?

I haven't found an original 97 radio yet. I want to make sure that I wouldn't have to make any mods/wiring to install the factory radio.

One more thing, like the newer radios of today, would I have to have the dealer reset the 97 radio I wound install?

tna