Detecting YUN REV

Hi,

I have a bunch of Yun's some are REV1 and some are REV2,
I'm running some software on the Linux side that works OK on both but requires loading a slightly different configuration, so what i'm looking for is a robust way to identify the REV on the linux side.

so far i'm achieving this by checking the busybox version
using: ls --help 2>&1 | head -1 | awk '{print $2}'

this works fine but was hoping there was a more robust way... (that will not stop working when i upgrade the image)
any ideas?

Thanks,