Difference in grips for Ruger Mark 1,2,3?

[David S]

I know the functional differences of Rugers mark 1, 2 and 3 each progressivly adds a new feature....
but im curious to see that on Rugers site they list grips that will ONLY fit the mark III and not the Mark II......
i understand the difference betnwee the mark 1 and 2 is the slide release. and the mark 3 adds the mag release, but why wont the grips on a mark2 fit a mark3?

 

[ball3006]

Probably doesn't have the slot...

for the new mag release on the Mk 2 mags. A Mk 2 mag can be changed to work in a Mk1. You need to move the button to the other side......chris3