I guess I'm not as lucky to have it hand written penned date code on the chassis. I don't see it. I did call MESA a while back when I purchased the amp used to try and find out warranty info and when I gave them the serial number they said they couldn't tell from that. Kind of confirms the "random" statement made in the previous post. I found this hard to believe especially for a quality company like MESA. Many companies use embedded date codes. Maybe they just don't want to give that info out. Here's what I think .... look at your transformers specifically the last 4 digits. Mine are like 0622, 0615, 0623, etc. My guess is that is the date code for manufacture of those items in the production flow. i.e. 22nd week of 2006 equates to 0622. Reason I believe this is because when I looked at other MESA LSS at guitar center the same area numbers had 08s and 07s. Check and let me know.
PS -- I do also remember coming across an article on the web where there was a date code list for Celestion speakers, but they used a alphanumeric code like 22BR and you had to go to this cross list to figure it out. Any hoo that should get you close.