There's already a thread dedicated to your question: http://forums.windowscentral.com/nokia-lumia-830/345740-product-codes-better-terms-updates.html AND you created it...you won't find a different answer posted here.
No one KNOWS for sure so it's speculation at best. It "might" be the Telus 059W5M5 because I received the Denim update on the 17th of March, but who knows when I'll get 8.1 Update 2...These questions seem to useless. No one really knows but I guess they keep being asked just to calm nerves, and any "answer" will do even if it's not accurate. Good luck :wink: