Steering U-Joint

[mkyhmltn]

Did the search with no luck, so here goes. I am building an 86 reg cab truck with SAS and High steer with the 86+ IFS power steering box. I would like to get rid of the rag joint and replace it with a u-joint. What I need to know is the size and spline count on the input shaft on my box so I can get the right size joint.

Thanks for the help.