subs need 1.65 cu ft of air space in a vented box

[GueroZ28]

What's your vehicle and amp?

.2001 durango with a 3rd row seat.. my amp is a db drive 1050.1 i think it says

[GueroZ28]

And how do i find the dimensions of the port in the center? Also can.the box face up since there isnt much space or is the sub fine being like 5 inches from the hatchback