2005 T&C speakers not working
 

I just got a 2005 T&C van. It has the factory 6 disc CD changer. Both door speakers do not work, and both dash speakers are real quite compared to the rear ones. Trying to figure out if it is the speakers or radio that is the problem. Any ideas on how to tell?

I am think about getting an aftermarket radio. Besides getting a wiring harness are there any tricks or tips to changing out the radio. Any problems with having 4 front speakers instead of the normal 2 on most radios.


Thanks,
Ben

Also how do I know if it has the Infinity streo.