Great, very useful tools. I've never seen any with depth stops like that. I own two by a different maker, one with the hahdles straight out behind the jaws, t'other with the handles at an angle.
Somewhat to my surprise*, Irwin Tools has continued offering Vise-Grip-based versions of this tool:
http://www.irwin.com/tools/locking-tools/the-original-locking-sheet-metal-tools. And, of course, the pro tool companies for tin benders - Malco, Klein, and so on - still make them.
*And why would I be surprised? Because the trend in the corporate takeovers of tool companies over the last 20 years has been the elimination of anything the new conglomerate can't sell thousands of at Home Desperate and the other big boxy stores; and these are pretty specialized tools for the homeowner doing a little work on the house.