I installed a crysteel dump body with fold down sides, and I love it. If there is one feature to get, it is fold down sides. Its like having 2 bodies in one. Another option is the Stahl unit that has a utility body outside with a dump insert. It is a lot of money, but again one truck doing the work of two.
If I were to really dream big, a swap laoder system is tops. Any body you want on and off in less than 1 min.
Well depending on trans type, you have two options. PTO driven off a manual tranny, or electric over hydro. Electric will be more cost effective, any body out fitter should be able to price a system for you. The body with hydro will set you back 3-5K depending on options.
I have seen and Airflow body and i thought that they are pretty good 9' with the low sides can build them up with wood and gussets plus the tail gate has pins on springs that can be opened by hand and not having to take a hammer to get them out to drop it.Take a look at them think that you will like them.
I installed a kit from Northern Hydralics. It uses your existing bed and electric/hydralic. It works great and was easy to install. At the time the kit cost $750, now $850. Some material hangs behind the wheel wells but it is better than shoveling the whole bed. Eric