Mk80 family bombs are produced in sections, with threaded holes at front and back for mixing and matching add-ons like different guidance sections, fuzes, tail fin kits to get different ranges and types of performance, et. al. Here’s one application:
Raytheon Missile Systems in Tucson, AZ received a $16.9 million firm-fixed-price contract modification for 139 guided bomb unit 28C/B guidance control units and tail kits, which appear to be dropping slightly in price. The 5,000 pound “bunker-buster” GBU-28C/B, also known as Enhanced Paveway III, possesses a laser guidance capability that can work without GPS and correct right up until impact, aided by JDAM-like Global Positioning System targeting that offers precision accuracy through any weather as long as the satellites survive. These improvements are being retrofitted to existing weapons via the Dual Mode Laser Guided Bomb Program, and the modular nature of the bombs makes this a simple switch. The GCUs screw into the front, and the tail kits screw into the back to provide the required maneuverability.
Total funds have been obligated, and work will be complete May 2008. The Headquarters Air-To-Ground Munitions Systems Wing at Eglin Air Force Base, FL issued the contract (FA8681-05-C-0075/P00016).