Hi Dave. What many do is to purchase a standard Tamiya tractor 6x4, Scania or MAN, and ad the cab, drivetrain and more to the Servonaut dumper kit. In case of the Actros there is currently just 4x2 tractors from Tamiya, so one have to purchase a third axle and rear suspension for 2 axles. Optionally there is the Hercules Hobby Actros 6x4, which is a copy of the Tamiya kits.
Now, a dump truck based on the standard Tamiya tractors are a bit like 'Bambi on ice' when put in to 'off-highway operation', according to many, me included
But on a good even road it's okay.
So, many start adding option parts, step by step, like
1. Change the high rpm original 540 Tamiya motor with a lower rpm, 6000-8000 rpm, higher torque motor. (Or get rid of the original motor and 3 speed transmission, which don't do much use in a dump truck and takes a lot of space, and install a 1 speed Servonaut GM32U390, + bracket, 7.2 V, the 'Rolls Royce' optional Tamiya transmission in Europe. (or GM32U450, 12 V, even stronger)
2. Replace the original hard rear tires with the soft Hauler 1.7" tires from Rc4WD, for a lot better tracktion.
http://store.rc4wd.com/Hauler-17-Com...res_p_728.html
3. Replace the original rear suspension, with very limited travel, with a much better one, like this one from Wtb (other dealer as have it), my number 1 rear suspension;
http://www.wtbcar.com/shopping/index...&product_id=95