Well, I did what I should have done first -- called somebody and had them
take a tape measure to one.

The folks at the nearest place that might have one (Rockler in Portland,
200 miles away) were very tolerant of my inane question. The 9 inch Pony
vice they had on hand would fit a bench up to 2 1/2 inches thick. My
design is currently 4 1/4 and I'd like to make it 4 1/2. I'm going to
have to think about how I'm going to do this a bit more.


--
Frank Stutzman