could anybody tell me if this is/isn't a Graflok back?

That's a spring back. A Graflok back has a sliding 'keeper' at the top and bottom of the ground glass to allow removal of teh GG assembly so you can attach a roll-film back or other Graflok compatible accessories. Here is a Graflok back:

http://cgi.ebay.com/GRAFLEX-4X5-GRA...5|66:2|65:12|39:1|240:1318|301:1|293:1|294:50

 

Definitely spring. Graflok has 2 lever arms which you can depress to allow the back to be slid off completely.

 

The camera you're showing is an Anniversary model. It's not too likely you'll find one of those with a Graflok back. You probably want a Pacemaker Speed or Crown Graphic (depending on whether or not you want the internal shutter) but even those are sometimes found with the Spring back. The Pacemaker features more movements than the Anniversary. The Anny uses simple to make yourself wooden lensboards but the Pacemakers use formed sheetmetal ones (although you can find them fairly inexpensively).

Why do you want the Graflok, by the way? The only clear advantage to it is for using roll film backs (I've yet to use mine - if I want to shoot 2x3 I'll pack a 2x3 Graphic - if I'm lugging around a 4x5 camera it's to shoot 4x5). Double sided holders work with both (as long as you don't get the ones for a Graflex back - just to confuse you more - those holders will have a groove down each long edge - stay away from cameras with those backs) and I think a Grafmatic will work in a spring back (it's not that much thicker than a double sided holder)

Dan

PS If you're interested, I have both a Pacemaker Speed and Crown in 4x5. I might be willing to part with one of them (not really sure why I need both)