blowthrough

I was wondering how to do a blow through i have started threads on here before but havent got a real answer so can someone tell me or show me what one of these things look like? and how to i attach it to my cab and bed so that it wont leak?

A blow through is nothing but a hole in your cab and bed. The cab and bed is sealed with a rubber camper shell boot that connects the hole in the bed and hole in the cab which are cut the same size. Your box is in your bed which should be built to blow though into the cab. As far as attaching a blowthough like you asked about, it is just a hole you seal up with the boot. You dont buy a blowthough or attach it to anything. You make it with a sawsall. Designing the box to work with the hole you have created is the hardest part.