I bought one of these a while ago, and while it is for .30-06, it worked fine with my Izzy .308. The boxes won't fit without removing the cartridge stops, but if you're determined to use one you can always get an extra set and cut them down to work with the boxes. I took a quick picture so you can see how much room is left on them. Also, as I'm sure you know, .308 is shorter than .30-06, so there's going to be a lot of extra room in these boxes. The belts will hold .308, but it's a tight fit. I had to go stretch each hole by hand to get them in far enough, and by the time I loaded the belt my fingers were a little raw.
Also, these belts can hold .45 ACP convincingly, enabling you to perpitrate the myth that a 1919 can be converted to yet another caliber, and also proving that I have far too much free time.
Don't mind the scratches on the side, there, this one's seen a few range sessions.