He drives a '92 Chevy pickup standard cab. He is a tall guy so he has the seat all the way back. There is very little room behind the seat. He is looking for a 10", or maybe even a decent 8" that will fit behind or under the seat. I was going to suggest the Pioneer shallow mount subs because they only require .35 cubic feet for the 10".
He already got ripped off here buying stuff from Best Buy. I told him to take it all back because he spent way too much, so he did. They sold him an Alpine Type E 10" for $140, and a Q-Logic truck box for $90, and the box wouldn't even fit. The dumbass at Best Buy told him that it would fit no matter what.
So anyway, he needs a sub, box, and amp. He has all the rest.