I am so happy the drive-on plate works for you. My father, SK KC0GKZ, welded that together for a field day years ago and we got a lot of use out of it. Here's to a great second life for it. I hope it serves you well. 
--
Charles Rich
AK4SR
Stem Ham Radio
https://www.facebook.com/groups/1460319574150873/

Hello to the list.  I want to thank those who responded to my call for help; those who replied to the list, and those who replied with a direct email.  A fellow ham and I agreed upon a swap of a mount for some ham-related equipment.  It was a great day.
 
As an update, I used my Spiderbeam pole with the new drive-on mount.  It was the first time I had used my fiberglass pole.  I did not know about the antenna fastener that would have been available when I purchased the pole.  But, sorting through my toolbox surfaced something that would work.  And, work it did!  I made 47 contacts (combined) on 40m and 20m.  Talking with another ham about the Spiderbeam pole he said that it looks like a cotter pin would work.  I'm happy with my "homebrew" solution, but will definitely check out the cotter pin suggestion.  Another great day for ham radio.
 
I've made reservations for two state parks near Corpus Christi, so more great ham radio days coming to the near horizon.
 
Have a great weekend.  vy 73 de David AE4LH