Originally posted by Scream
[.and unless you have airbags you probably need to take into account the drop of the rear end from the tounge weight. [/B]
Put your trailer on level ground (not hooked to a vehicle) and raise or lower the tongue while looking at the suspension shackles, tires and wheel wells to determin where level is. Measure to top where the ball will be in tongue.
Take into account sag if you don't have bags. Put the hitch you have on now and measure to top of ball, hook up boat and measure again to find out how much truck went down. The rest is basic math. Every rig is different.