I believe this is an '84 - Pro Tour 15:





'84 Centurion catalog:

Centurion Bicycles 1984 Catalogue

This came to me with the same build as in the ad. Tange Champion No. 2 tubing. Unfortunately, the previous owner serviced the BB at some point, left it a bit loose, and the little ring chewed into the chainstay:



I actually rode it like this for a while after removing the small ring (might have gotten lucky there...), then had a bit of an incident with the rear dérailleur exploding on some single track. Long story short, I wound up bending the rear triangle a bit and decided it was time to retire the bike (due to the nick in the stay)...

Any ideas as to what this 'L' indicates? Date code? This is on the drive side. English BB, so L ≠ Left. NDS cup does not have a similar marking. Edit: perhaps Left hand thread...