I just do the test, I try to make look like the real truck... If I go for 6x6 the motor is not strong enough, other wise drive shaft between 2 axles is too long then it make the distance between tires is too wide, not look like the real one. I may install shocks on first axle, the back one I want flexible to go on rough surface.
I will install new ESC/steering servo and sound module too (from Ford F150 Banggood)