A quick internet search did not produce any usable results which I'm sure does not surprise you.
Most here would suggest just getting an aftermarket radio as not many are fans of the quality of stock headunits.
With regard to stock units, there are a small collection of variations that were factory, touch screen and gps versions. I don't think there are any actual differences in individual models other than minor iterations.
That being said, some versions of stock radios require a security code. I think it's only the touch screen and above but I'm unsure.