Photos please. Which Punch model is it? Is it this thing? http://www.crutchfield.com/S-8tYU97JIfB3/p_575P30012/Rockford-Fosgate-Punch-P300-12.html
May want to get away from that design and go with something different. Throwing money at a $300 item when you can put new or used box together with an amp... The later option would be better. I'm a big Rockford Fosgate guy and still rock their amps, but am not a fan of their self powered boxes. If it's for space, I completely understand but that didn't stop me from putting 2 10" Boston's along with an amp and a spare battery all behind the bench seat. There ain't much room in an 89 Z-71 single cab.