Spinnaker Pole Roll Pin

Hi all - does anyone happen to know the diameter of the stainless steel roll pin that holds the spinnaker pole end piston in place - this is for the original 3" aluminum OD pole? Somehow that piston got loose and the piston spring, well, sprung out when the roll pin fell out. My friend fabricated a new spring for me and I was able to find a suitable-ish replacement pin, but they aren't stainless and they are already starting to corrode badly. Thanks for the help.

I have a spare old spin pole. Take a look let me know if it's the same end. I can strip it for parts.

That looks very similar to my spinnaker pole, let me take some measurements of the piston and hook diameters and I'll get back to you. Thanks!