2006 E150 Speaker wiring advice
 

I recently bought a 2006 E150 cargo van. I can see wiring at the top of the driver’s side wall going back to rear doors. This van has a simple AM/FM radio with speakers in the front doors. Is there a chance that there are speaker wires in the bundles of wires that are routed to the back of the van? Maybe they are terminated in the harness behind the driver's seat?