Is there a way to tell how old my fuzes are?

Hi I have multiple Sansa Fuzes. Two I bought brand new and 4 second from ebay, or thrift store. My question is: Is there a way from reading the back of the mp3 players that I can tell how old they are (when they were made)? Once I find this out I can use the older ones first before their battery life gives out. They are


Is this the order they were made? Is there anyway to find out what year they were made? Thanks; 

I contacted SanDisk and recieved following answer:

I understand that you want to know the year of manufacture of the players you have so that you can use them accordingly. Please note that we do have multiple codes on the product through which we can get the details. Unfortunately we can not share the information with the customers. 

I don’t want state secrets.  I just wish to see if I can find out which ones are the oldest.

The V2 players were all made after the V1, so if any of those are V2s, they’ll be much newer than V1s.

And to expand on Saratoga’s advice, check your firmware version (Settings > System Settings > Info). If it starts with 01, it’s a v1; if it starts with 02, it’s a v2 model.

Thanks guys.  I knew about the firmware, but what with all the updates I thought it would be hard to nail down.  On the oldest one I bought brand new BI0910BMXK  an 8gb it has firmware ver.2  I wonder if I had put on wrong firmware update by mistake at some point?  It’s well used, well loved, but the audio jack loose.  Funnny thing is it has the 2nd lowest number on the back…  I was hoping the numbers on back would go up as they got newer?  I don’t know why Sansa couldn’t tell me if this was the case, or not.  It’s not like any of them are under warrent anymore.

If they’re all v2s, then they’re all post 2009 or 2010 (I forget when they stopped making the V1).

You can’t put a v2 firmware on a v1 player by the way.  That would destroy it, so the v2 checks that you have the right firmware before updating.

I guess that leaves me with 3 V1 and 2 V2.  I wonder what all the info on the back means (other then 4gb, 8gb, etc.)  I hope I get several more good years out of them.  It is a shame they stopped making such a good product.  Not many mp3 players work so well and can use a 32gb card for such a resonable price.