I inherited a really nice Bausch & Lomb Custom 10x40 (armored porro, model no. 61-1046, with Nat'l Audubon Society endorsement badge). I'm curious about the year of manufacture. A couple of other posts on these forums provide approximate years (mid-to-late 1980s), but judging from other online sources this model was still being produced (or at least sold) in the 1990s. Is it possible to ascertain a more precise year? The prefix 'AB' in the serial number (#AB02535) doesn't appear on any online B&L serial number lists that I've found (the lists appear to end before this model was made).