Don - your king pin specs are found in the GM Heritage Center
1946 Chevrolet Truck Data PDF.
Screenshot below highlights the details:
King Pin Diameter = .9210" - .9214"
King Pin Bushings Inner Diameter = .922" - .923"
King Pin Bushings Length = 1 - 17/64"
PS - I moved this to the Driveline forum where it fits best.
