I got a kick out of this article, "Lords of the Springs", in Premier Guitar. Some of the units are well known, at least to many members of this forum. Some had the light bulb going off in my head ...."Oh yeah. I remember that thing! How did I forget about that?" Some I had never heard of, and some really have little or nothing to do with spring reverb. Fascinating article, to me, nonetheless.
https://www.premierguitar.com/articles/27240-lords-of-the-springs?page=1
—Bob