Is there a big difference between the THX and non-THX door speakers? Lincoln parts gave me a THX speaker when I told them I had the non-THX system, didn't discover it until I had the old speaker out, so I said screw it and installed the THX speaker. Walked back and forth from passenger/driver doors, didn't notice any sound difference.

if you didnt pay any extra for it, it should be fine. if unsure, see if you can see the coil resistance on it, usually on the magnet. I'm pretty sure it should be 4 Ω (ohms). You can match it to your old ones by taking a resistance reading across the leads.