Looking through the MVWC past auctions, I see one of these was sold at the 2007 Vern Nail auction. (#906-2) It was listed as unknown unfortunately, so that was no help. It does appear though that there might be some sort of little brackets attached to those holes at the ends of the plier handles? Hard to say for certain.
Bus photo from 2007 MVWC auction

http://s222.photobucket.com/user/buswrench/media/Nail-2007/0898-907.jpg.html
Good lord, those are some over-engineered pliers in that picture! Wow...
An engineer knows he has reached perfection not when there is nothing left to ad, but when there is nothing left to take away :P
I'm sure they were all designed to do all aspects of their own certain task... But still o.o
I do like the #900 with the little baby vise on the end of one of the grips, that's adorable... I wonder if the jaws-side would fit into an Anvil hardy hole...