Chris, you're spot-on. That is exactly what I'm looking for. I just remember the actual head having about a 1" long female threaded hub on the back side to receive the 5/16" threaded rod. That's why we nicknamed them "mushrooms", because this hub looked like the stem of a mushroom with the obvious mushroom head.

I installed hundreds of pay phones back in the 90s. I can't believe that I don't have any of these things left or at least a name/manufacturer for them!

And they make fun of people for hoarding. If I had only kept those invoices or catalogs. Wait! I do still have my full set of Sprint/North Supply catalogs in storage and I purchased them through SNS. The end may be in sight.

Ed Vaughn, MBSWWYPBX