The first of 4 numbers in the family hierarchy represent the location of manufacture and manner of distribution. A "2" or "3" means it is hand milled through the USA custom shop. Sold only through Kahler International Inc., it is stamped Kahler "Made in USA". It is known as the "Professional" version. A "4" means it was factory made in China under exact SAE specs for Kahler and is primarily a lower price point trem for a guitar manufacturer to use. Stamped the "X-Trem", they are not sold thru retailers. A "7" means it was factory made in the USA and is the retail version most players will see. It is stamped Kahler "USA Hybrid"... Hybrid because it incorporates a locking screw to lock it into a fixed bridge. It's a full trem and a fixed bridge in one.
Bob pointed me toward ABM and cos I like schaller, the 3Ds. Its a bit hard to find a photo that doesnt make them look like tele bridges, but once you do - very nice solid looking chunk of bridge with good adjustment capabilityhttp://www.thomann.de/gb/schaller_1477_3d6_steg_black.htm
Thanks Wez. Korean was just best guess. Probably would have been better not to state it as fact. Any issue with the cast models, quality wise?