The Pachmayer Presentation and the Gripper Decelerator both fit just fine and work quite well.
I have, and have used both of them on my Kodiak 44.
For me personally the Gripper Decelerator was more comfortable for shooting full power loads and is what I generally keep on the revolver.
There is a spot at the back of the grip where there would be metal on a regular Redhawk that you can feel a soft spot if you push on the back of the grip looking for it, but in normal use you would never realize there is a void under the rubber.
Gripper Decelerator :