Beginning with the 2007 model year the heater configuration was changed. It no longer screws into the block. It just slides into a hole in the side of the block below the thermostat. There is a retaining clip on it that snaps into a notch on the block. The heater has no direct contact with the coolant.
Can you provide a link to that information? When I look at Kat's application data on their site, they show 2007 using a threaded freeze plug and the model(s) heater (11484 and 11455), that screw into a freeze plug threaded hole.