1700+ and 2100+ help

ok i know i need to get the JIUHB for the 1700+ but what are the numbers like 0310wpm/xpmw, 0302, 0307? and which one is the best one? and also is the 2100+ AIUHB 0302 good?

The four numbers after the stepping code are the year and week the core was manufactured in yyww format. The remaining four letters are 95% mystery. It is widely believed that the third letter relates to the wafer quality used for that batch of chips. Wafer quality of "A" is the best, "M" is a typical/average chip, "Z" is lower quality and numbers are REALLY bad. I have not heard of any "exceptional" weeks or any weeks to avoid, but others here may have something to say.