Sneaky Microsoft: Still Shipping Zephyrs
In my Jasper hunting I came across a strange beast, I found an Xbox 360 Pro with lot number 0843X. I figured it was new enough that it could be a Jasper, but looking at the 12V current rating I found that it was a 16.5A unit. I thought perhaps it was mislabeled and I'd heard about some newer systems having a 16.5A 12V rating, so I thought I'd buy it and take a closer look.
Once I got it home I confirmed: the machine was a Zephyr, that's the original Xbox 360 hardware with HDMI support, meaning a 90nm CPU, 90nm GPU and 90nm eDRAM - the very configuration most likely to Red Ring. I'm guessing it's a reworked Xbox 360 that never made it out of the factory in the first place due to an instant failure; something Microsoft fixed and sent out at a much later date.
Even if you don't care about getting a Jasper, it may be worth looking into what it is you are getting to make sure that you're not stuck with a box that's more likely to fail.