Has anybody had much experience with the space in a Dodge 4-door quad cab vs. the space in a Chevy 4-door pickup?  I need a full 8 ft bed but want enough space for an adult or two in the back for long drives.  I've read about the mega cab long bed conversion, which looks good, but in the long run it might be just as easy to put a Cummins 5.9 in a Chevy that's already built to the right dimensions.  

actually in the long run its prolly cheaper and easier to buy a mega cab that is already converted to a long bed  

The Dodge Quad Cabs are a little on the snug side. If you're going to be hauling mostly kids, it shouldn't be a problem, but if you're going to be driving around a bunch of adults, the Chevy Crew Cab is the better of the two. The Mega Cab is like a limo. Unbelievable room. But they don't make them from the factory as long-beds. However, there are some companies that do coversions to make long-bed Mega Cabs, like you said.  

my brother in law has a quad cab and we test drove a chevy crew before and honestly they both seemed about the same. i like the way the dodge back seat feels more then the chevy. the chavy may MAY have had about 2 more inches of room but im 6'1 and have plenty of room in the dodge.  

Im debating the same thing...I thought about it and think I am going to stick with getting a truck after all and my parents went from an escalade to thinking of buying a truck at the same time as me to get a sick deal..So I wanted a mega cab for the rear room and we take long trips but I want a long box...but lets be honest a long box add on is like driving a limo around...well I haven't driven in one but they seem to look like you cant go off roading in the damn thing...so im looking at a GMC/Chevy 4 door long box...so anyone have experience driving a mega long box...I don't want to spend a fortune either.  

Can anyone help with this?  

Well, if you're buying brand-brand new, you'll just have to get used to it. Too bad GM quit making Quadrasteer. Those things were the best of both worlds.

Yeah, with a long-box crew cab, you're just going to have to get used to the length, not to mention look for big enough parking spaces. As long as the off-roading you're doing isn't too extreme, you should be fine, but it's not going to have the same maneuverability as a Wrangler. Once you're on the road, you can't really tell. It's just U-turns, parallel parking and looking for spaces that are a bigger PITA in CC long-boxes.  

ah I was just wondering about the backseat size of the quad cab dodge compared to the crew cab in the GMC...I drive a lot and would like to have a large backseat. I want a 4 door long box..but I need to make sure I have enough room for people in the back.  

I have taken many, many 4-5 hour trips out to the river in the back of my father-in-law's '07 Sierra 2500 Crew, and it's no more or less comfortable than a normal car. There's plenty of room back there.  

Aw I ment what is it like if you took a 4 or 5 hour trip in a dodge Quad Cab..I have a 2001 super crew f150 right now and its not bad..