Hi Gene,
The Chev Crew Cab is bigger than the megacab isn't it?? To late now I guess... Congratulations on your new truck anyway...
I put airbags on my dually... not necessarily to carry the load, but to make the ride better. When loaded and ready to go,, my truck was about 1/2" from the overloads.. so every little bump or dip in the road it hit the overloads and clanked and made for rough ride. I installed air bags.... took the overload brackets off the frame so I did not mess with the springs. Now I get really smooth ride with about 30# air...
Jim M