I picked up a shallow Kenwood XCELLON 10" Sub. perfect for a ranger. The box is built to the smallest specs of a sealed box, but can be put right where your tire jack goes. I carry a tool box in the back anyway so I was able to save my seats without losing much space if any at all.
I am using an old Kenwood amp to power it, just had it kicking around but the sub pounds!!! Enough to make everything in the cab vibrate uncontrollably...The amp i think is a about a 400, but although its old it was a high end amp in its day. We installed the amp under the driver seat. (It's the least used by passengers.
I'll be doing a post in a sec with a few more. I keep forgetting to take pics now that I added the grill and have cleaned up the amp a bit.