Rockford has some shallow mount 12's out now. I have been told that they sound great and do not require alot of air space. I'd recommend them. The single cab silverado's suck for installing subs, I have an 03 GMC and I am working on the sub box in it.
I just swapped out my JL 10w6v.2 for a Boston G1 10. I'm selling it now and lookin to get a Kicker CVT10 for myself. Great sounding subs. I heard a single 12" CVT in a celica with 300 watts going to it and it sounded very nice.