Pete sub location in bunk?

Hey guys & gals Happy New Year!

Well my concert class head unit finally died after 1 million plus miles & was replaced with a Panasonic aftermarket unit from Peterbilt that is rated 50W x 4 with 16W x 4 RMS. I know it has an amp in the overhead console (have seen it) & was told it had a sub in the bunk. With the new head unit i gave up some sound quality but got an aux input & backlit dispay again. I have lost some but not all of my super strong bass from the sleeper now & wanted to tear into it & make sure it is still firing. The new unit plugged in so no cutting/ splicing was done. Any idea where to start? I've looked under the bunk & don't see any dead space. Thanks for your help.

 

Thanks Hurst. When i get back to my truck on monday will take a better look. I know before it would make things rattle & shake if i cranked up the lows & now just doesnt have that thump.