Place a 1 before the 4 digit date code, apperantly they continued on after Dec 13 '88 with a 5 digit Julian calendar. For example, my 1994 46RH is stamped 1737; make that 11737, and enter it into the calculator on maxwedge.com (I'd post a link, but I'm not smart enough to know how), and it comes up Sep 15 '93. It's been correct on my other 46RH and my A500. The one problem I found, however, is that it didn't work for the numbers on my 46RE cases. Gave me build dates of late '92 and early '95. Not the fault of the calculator, the dating system might have changed.