poly box ? (it's a battery in the back question)

Something like this is NOT NHRA approved: http://www.summitracing.com/parts/sum-g1210/overview/

Something like this IS NHRA approved: http://www.summitracing.com/parts/mor-74051/overview/

The difference is the NHRA approve ones are sealed, and vented to the outside of the car. To be NHRA legal you need a minimum of 3/8" bolts attaching the battery to the frame.

Complete kit:
http://www.summitracing.com/parts/sum-g1231-k/overview/