Thanks all.
Grant a pup would be a cool addition to your truck and you'll have the power to pull it too. Does your donor truck have a gravel box? If it has the hoist and box already set up, that will be a huge head start. My trailer is set up as a dump as well, but I made it a flat bed because it's a little more handy for the type of business that I'm in. The brakes are vacuum over hydraulic. In one of the pictures you can see I used a vacuum can and master cylinder out of an early 70's chevy. You have to modify the insides of the can a little in order for it to work. Inside the cab I'll have a hand operated brake valve to apply the trailer brakes.
Grant/Speed, the drop axle is steerable, I just used the front axle and springs from the truck the way it was. I haven't tried it yet with it down as I still need to plumb the hydraulics to the back of the truck. There are lots of different ways to make it lift, (air, hyd., manual, etc). But I figured that since I had hydraulics to the trailer for the dump I'd use hydraulics to drop and lift the front axle. One thing that makes it a little more complicated is that the hydraulic systems typically set up for the hoists are single acting, meaning the pressure line also acts as the return line.
Paul.
