Will these new E2 grips fit a older 226?  Thinking about changing the old ones out,

Yep!

ETA: There are a few springs and other stuff you might have to change out to make it work, but it is easy to do.

This:  http://www.topgunsupply.com/sig-sauer-e2-grip-kit-p226.html



Plus this: http://www.topgunsupply.com/sig-mainspring-seat-new-style-p220-p226-p228-p229.html


and this: http://www.brownells.com/handgun-parts/frame-parts/mainspring-parts/mainsprings/sig-mainspring-kit-prod16487.aspx





Those are the three pieces you need to convert an older P226 to the newer E2grips.


Depending how old your Sig is, you might be able to sell the old grips to offset some of the cost.  


The W. German grips are in demand over on the Sig Forum.




 
 

Also, a word to the wise. There is a trick I learned on one of the sites, as to putting on the E2 grips that saved me from replacing the trigger spring(although I did have to replace it). Use a credit card, driver's license, etc., something thin/stiff, and place  it over the spring/frame as you put on the E2 grip. The grip will be a tight fit and will press against the spring and poss. warp/compress/destroy it enough that your trigger will not reset normally when you reassemble the pistol. It is a great idea that someone came up with and will save you some aggravation and money. Ask me how I know.

How much narrower  is the E2 Grip from that stock on the MK25 ?