Don't let them fool ya. My sister has a 98 quad cab and while the infant seats may be fine toddlers will have a tight fit. In California, children must be in carseats until they are 60 pounds or 6 years old. When you start with an infant, they are usually in the little carriers that fit no problem. Those go up 'til the child is around 20 pounds in weight. Then they are moved up to a rear facing full size car seat, a baby's neck still cannot handle an impact if forward facing at this point. Here is where it becomes a tight fit. Your only option in a quad or club cab is to put the seat into the center of the rear seat with the front center armrest folded down. Most likely the child will not have any leg room. Once the child grows to the point that the full size carseat can be forward facing it will still have to be forward facing with their legs up front on the folded down front arm rest.
My daughter will be three years old in December, she weighs 38 pounds and is 36 inches tall. In my diesel suburban, she sits right behind the driver's seat and I constantly have to remind her to keep her feet from kicking the back of my seat, and remember, there is much more space between the front seat and back seat of a suburban than there is in a quad cab. My ram is a regular cab without a passenger airbag, so she rides in the passenger seat with a carseat with no problems.
As I also have a 5 month old baby, so with a family of 4, we can no longer tow the camper with all of us in the truck, so we have been looking at the new powerchoke and the '04 ram. So far the wife wants a pherd (a real crew cab), I want the cummins. If you are going to buy a club or quadcab truck to have your kids in, just keep in mind that while they may fit fine at first, it will soon become a very tight fit. Just my $. 02 worth. Good luck!