What is it?

I thought I thought I was pretty efficient at researching the web for information, but I've run out of energy trying to identify this item.  A friend bought this item at an estate sale just because it seemed to be somewhat unusual. The seller had no information regarding its time of usage or the name that was stenciled on the top cover. My Mister thinks it might be some sort of munitions container. I found locker boxes, ammo boxes, gun and rifle boxes and many other similar containers but none as slim and as shallow. My thinking is that it could be for a field spotlight or a surveyor tool. Can anyone help? It measures 45 inches long and is only 4.25 inches deep. There is a handle in front and one on each end. The photos she took show it on her kitchen floor and standing upright. Army and Navy surplus sites don't show it and I'm totally at a loss to give it an accurate name.