Finally got one. I can confirm K=2.71 now. Seems there're still plenty of
them in BB. For the curious people, here is a list for the firmwares and
letters on UPC:
* A: 1.50
* B: 1.51
* C: 1.52
* D: 2.00
* E: 2.00
* F: 2.00
* G: 2.01
* H: 2.50
* I: 2.60
* J: 2.70
* K: 2.71
* M: 2.80
* N: 2.81
