This would tell me that the L stands for the years 2001, and the O stands for a month 3 months past December. The code follows the format: XXXYYZZ, where: ***** = a two or three digit number (possibly four on newer amps) indicating the manufacturer.
(refer to the chart shown below) YY = is a one or two digit code indicating the year of manufacture.
If it's a one-digit number you need to determine the correct decade of the amp some other way.
ZZ = a number from 1 - 52 indicating the week of manufacture.
If there is no sticker, contact Fender with the serial number and they can tell you when it was made. Off-hand, have you ever seen any Fender Serial Numbersthat include date codes?