C42 part number wanted

[BCA]

A large “captive locking screw” that threads into the ATU and slips onto the spike (support, antenna, ZA29831). What is the part number for this “captive locking screw” - as it is described in operating instructions for C42 in 1/4-ton , 3/4-ton and National Survival manuals. The threaded stud is a British thread. The “ears” on this screw are often bent close to the sides so it can be turned and tightened when the ATU is being attached on the spare tire bracket antenna mount on Canadian jeeps. Finally why does the spike have crude threading: it simply slips into the lower hole of the captive locking screw when putting the ATU on the ground. A set screw clamps it in place.