Yep, 1100 cubes of bigness. Pretty advanced, too, for WW2...dual overhead gear-driven camshafts, multiple carbs. Like a hot-rod motor, only MUCH bigger. Contact me if you want some measurements. Up here at the Oregon Military Museum they have three or four of the GAN Pershing versions sitting on pallets. The differences between the GAA, GAF, and GAN are minor. I can probably arrange to get in there with a notepad, tape measure, and camera to document the thing.
Greg