[Synchro909]

I made a set of rods on tapered bushes to fit in the holes and mounted the axle in a vice so that the king pin eyes were horizontal (checked with a straight edge and spirit level). An eyeball is all that is needed to see if the axle is straight and that it isn't twisted. To check the king pin inclination, The rods were about 1.4 m long (4'7") I dangled a plumb bob from the top of them and measured the distance from the string to the rod at the bottom. 1.4 X sin 7* = 0.17m. In the old imperial system, that is 4.33". Simple trigonometry.
I did 2 axles. Both were twisted and had an inclination of nearly 8*. Without a press, it was more than I could do to straighten them so I went to a guy who does standard axles and ones for hotrods. (He puts up to a 4 1/2" drop in them.)