I picked up a Pioneer Shallow 8" woofer the other day and a Kenwood amp to go with it. More response than bass is what I was after. With the limited space in the brumby I set out to make a box. I didn't want it to be to one side of the cab, even though it wouldn't make much difference so it is sitting directly over the transmission tunnel. Doesn't need a big box, recommended volume is 0.4 cubic feet for a sealed enclosure. Fits quite snug. Here are a few pictures so far.
Tunnel and back walls.
Box built and made airtight
Next up will be to get the wire connectors on the side of the box put in, get the amp installed and then cover the box in something. Haven't decided yet what though. I might wrap it, the centre console and head unit fascia in vinyl. Will keep this updated as I get it done.