Where is the factory amp?

[91EDB]

I tried searching and didnt find anything. I have a 91 Eddie Bauer, and it had an aftermarket deck in it. I installed the factory deck, and found they ran different wires from the deck to the speakers, and cut the originals. well now running from the wires directly from the factory deck to the speakers I get almost NO sound. So I need to figure out where the amp is, to see if its bypassed. Or should I hook the original speaker wires up to the factory deck? I dont know why the cut them. any ideas? Also do I have a sub in here? if so where would I look?

 

[EMG7895]

the amp is in the back of the truck behind a plastic panel under the window on the right side (looking at it from behind)