What year and model truck?
What engine?

Rule of thumb is install the ball a couple inches forward of the center of the rear axle, I'm planning on 2" or 3" for my truck.

Be sure the bed is not so long you can't even hitch up or make a turn.
How much power do you have, is it even a good idea?

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-