What's available - good sub box - for behind the seat - looking at putting one 12 sub behind passenger seat. One is plenty for me. Any idea's what will work ...?

Looked on the Subwoofer section here but not much goes on over there about Lightnings or standard cab trucks...

 

try fordtruckworld.com in the classifieds..they have a huge audio section...and a lot of people sell boxes, etc.

you can probably get one custom made by a knowledgeable buddy or stereo shop hookup for 100 bucks or so...

i can get one done for the price of the mdf and a coupla beers