On the Wook, it says that they are "two wing-mounted laser cannons" - but in every model I've seen, there's nothing that looks remotely like a laser cannon anywhere close to the wings or wing struts.
In the cancelled game Star Wars Attack Squadrons, you could look at your fighter's front while flying and shooting, and that indicated that the two circular objects on the bottom half of the central strut/pylon were the laser cannons.
Anyone every thought about this question? Every source I've seen agrees that the bomber kept the two laser cannon design element, but it's never pointed out in the diagrams or cross-section books.

