Most common style end dump trailer in Alabama ???

was wondering what’s the most common style end dump in Alabama ? I was reading if you have a 6 axle combination meaning tri axle trailer + drive axle on tractor + steer axle you can gross 84000 on state highways plus a 10% allowance which will gross you out at 92400 so as long as you are 43ft long with 6 axles which is the FBF for 6 axles . So with that said in Alabama what’s THE MOST COMMON Length TRAILER ?? Common axles ?? Tri or tandem ?? and STEEL OR ALUMINUM ? Because I was told they haul a lot off dip rap down there but then some told me they use a lot of aluminum style end dumps so I’m curious what’s the most common style of trailer used in the dump game across Alabama ?