so through a google search I found one member
http://www.ar15.com/forums/t_5_13/142448_Cutting_Gen_3_for_Gen_4_mag_release_.html who did it, but his outcome required the frame to be stippled. I don't care for that look. so I went about doing it my own way.
Top is a extended gen 3, middle is factory gen 3, bottom is extended gen 4....cut the one parts off since the gen 3 right side is bigger then gen 4 right side
Gen 4 button part lined up with gen 3 right part sanded and made to same length as stock gen 3 release
Glued and had to shave a bit off the inside bottom corner of gen 4 part so it would clear a magazine. Tomorrow when fully cured I'll see how strong the bond is and if cutting the frame to accept is next
I used Loctite plastic epoxy, which says 24hr cure time so if my bond is solid I will tackle cutting my frame to accept the new release. I chose this way so stippling the frame wont be needed