AnandTech have posted their article on how to pick out an Xbox 360 with the Jasper board revision. It’s an excellent read with helpful tips to help you snag a Jasper.
Here’s the jist of it which I snagged from their article:
|Lot #||0842X or newer||Maybe|
|Xbox 360 Arcade Sticker Markings||XGX-00019||Probably a Guarantee|
|Xbox 360 Arcade Sticker Markings||Value Bundle 2008 E||Probably a Guarantee|
|Current Rating on 12V Rail||12.1A||Guaranteed|
If you need some help with locating these labels, check their article for the photos. It’s also worth noting that a lot of the Arcade units are Jasper models. This could be attributed to the fact that this revision includes 256 MB worth of internal memory. It’s also cheaper to make!