locating clamp?

[joykap]

Hi, I am trying to locate a stainless steel clamp that slides over 3/8" rod ring stand and clamps on to it with a thumb screw. I just need it to have a small arm that comes out a couple of inches and has a v shaped groove in it. I want to be able to rest one end of a mandrel up to a 1/4 inch thickness in size in the groove. The macine shop I saw it in said they got it years ago in a lab supply but I haven't found anything like it after days of searching. I would upload a crude drawing but I don't see that option on this forum. If anyone could direct me where to look I would appreciate it.
Thanks Joy