This was a General Motors Defence Canada attempt to improve the "exportability" of the AVGP family. It's a completely new turret with the new gun.
While the 6x6 wasn't exported to any degree by GM Defence Canada, the CMI turret/gun combination was later sold to Saudi Arabia mounted on a GM Defence 8x8 platform. Quite an effective gun with a full range of ammunition and still in production today.
http://www.army-guide.com/eng/product517.html