2009 GTX 155 shaft upgrade

[Gwgautney]

Ok so i went to change carbon ring on 09 gtx 155. Well the more i dug into it i realized that this was the problematic shaft and there were no parts for it. I decided to upgrade shaft. Everything was going good until i realized that the splines on the new shaft where it goes into impeller is larger and 28 splines where the old one was 21 splines and smaller. Long story short i just need to know Is it an easy deal just to get a larger splined impeller? And basically what year impeller would i need to order. Any help would be appreciated.