You already have latest version of camera raw for photoshop cs5.
(photoshop cs5 is not able to use newer versions of camera raw)
If you need to use cs5 for a newer camera not supported in camera raw 6.7.1, you could use the 8.3 dng converter to convert the camera raw files
to dng copies, which photoshop cs5 would open.
Yeah, I thought that was the case but just wanted to double check.
So in order to use the latest version of ACR I would need to upgrade to the latest version of PS?!
You can use the latest acr version with either photoshop cs6 or photoshop cc.
(You get the latest acr features in photoshop cc, while acr for photoshop cs6 is just updates for cameras with no new features added)
Also, lightroom 5.3 is another option.