At first, I thought it was a "G" model but a little digging shows it's an "H". The Harpoon missiles threw me off. I didn't know Harpoons had been fitted to the "H" model. That's a recent development.

It's hard to tell a "G" and "H" apart from a front view. The "H" models are the only ones still in service. They're distinguishable from the Gs by having turbofan engines instead of the straight turbojets. Turbofan engines have a larger air inlet that extends about 1/3rd of the way from the front of the engine as seen here.

B-52 Fact Sheet

The Harpoon anti-ship missiles on the pictured B-52 won't be needed since Afghanistan is land locked. I doubt they'll need the rotary bomb rack with the 8 ALCMs, either. That's okay. It frees up space and weight for iron bombs. BUFFs can drop a bunch of iron bombs. Very demoralizing.

More BUFF info with one correction. Just for the record, the second "F" in BUFF does NOT stand for "fellow."