I am thinking of converting my Gen 2 G21 to a longslide or building one. Lonewolf has the conversion, but says it fits the Gen 3. Is there a significant difference in the frames other than the light rail? If it is not compatible, is there a source for a Gen 3 frame? I will post the same question to them, but in my experience with manufacturers' lately, they don't answer emails in a timely manner, if at all.