Parts Express 269-472 6.5" Subwoofer by Pioneer for Pontiac
Despite having to solder to a weird place (see pic) using these subs is a breeze...provided you do some research first.
First IMO they are not subwoofers as they only go to 58Hz.
Second, they have a very limited frequency range, only up to 300Hz.
We have used these as reinforcement drivers for the 80Hz to 200Hz area in the deck of Anthony's car with good results.
Also, in testing, they sound great when used as a woofer added to a small FR driver.
Finally, at only $2.49 each, you have nothing to lose by buying a few and playing around with them.