The bolt has a 5/16" shaft and thread. It is long enough to pass through the tailstock base and stick out 1 1/2". The part that sticks out the front is 9/16" diameter, 1 1/8" long with a 3/8" length of 5/16" thread cut on the end. The back end has a large (1 1/8") hex knob held on by a set screw.
You remove the knob and install the bolt through the tail stock, then relock the knob. It remains in the tailstock. The 1 1/8" long portion is a spacer to hold the tailstock back far enough so the cross feed lock lever can be operated.