When to change control arm axles?

[65TRUK]

Hey guys, I'm completely rebuilding the front suspension on a 64 short bed frame (currently a bare frame). Though I have read a lot of articles regarding suspension builds, I have not read any technical comments regarding 'how to know when you should replace the control arm axles'. Note: before I removed the upper control arms I noticed just a little lateral movement of the control arms (probably 1/16 but not more than 1/8 inch) on both sides. Is this movement merely the axle shaft thread play between the axle cap inner treads and the axle shaft threads (which is the true control arm vertical pivot point/s)? I presume this thread play represents two components: 1) initial OEM thread play and 2) normal thread wear over a 50 year period?

I don't want to finish the rebuild and NOT change the control arm axles if I really should do so.

FYI, I'm rebuilding a 65 stepside on a separate 64 frame.

Thanks in advance for your thoughts, experience, tips, advice, technical data, etc.