Outer Limits 4x4 Board

hi, I have a set of Ironman 3 degress castor bushes. I do not have any instructions or manual so I don'tknow the how to measure it. Please help

Contact whoever you purchased them from and ask for the drawing/instructions, if they cant supply one phone me during B/H and i will mail you a tough dog instruction. www.superiorengineering.com.au