I'm also curious about Bausch & Lomb records from 1986 onwards, to complement information contained in 1990s Trade Catalogues (not always accurate or complete). I recall seeing, on another thread, that B&L Elites had PC3 phase coating from 1992 and my 1994 Catalogue confirms the Elites then had a 'P' after their model number. But the Discoverer roof models didn't have a 'P' suffix in 1994, so presumably lacked phase coating at that time. Indeed, on another Forum elsewhere, someone claimed PC3 was not applied to Discoverer roofs until 2001. It would be useful to have serial numbers and specifications for the years up to 2004, which I gather is when Bausch and Lomb finally withdrew its name from the binoculars market in favour of Bushnell. Incidentally, I don't recall ever seeing the 'P' suffix on any B&L Discoverers, nor even on the very last models marketed by Bushnell. Perhaps, like Zeiss, phase coating had become so 'de rigueur' in the 21st century that they didn't feel the need to flaunt it.
Finally, on the topic of serial numbers, it's not always obvious where they are on the binocular body. Have you tried to find it on a B&L 7x42 Discoverer? It was only after I'd deployed my big B&L magnifying glass that I discovered (pun intended) tiny words barely discernible on the face of the front hinge: fully bent down to minimum IPD, the word 'Japan' and a K inside a triangle; then fully bent up to widest IPD, serial no. AD 1344. My other one has the serial no. AG 4053. Can anybody tell me the years these were manufactured, and what the 'K in a triangle' signifies? PC3 coating maybe?