Cannonball will be a redeco of Prime: Robots in Disguise Ratchet, with a new head mold!

A fan who has received the magazine describes it as follows: Vehicle mode is black with silver for the fenders, bumpers, etc, and silver stylized skeletons drawn on the sides and top. Robot mode is also mostly black & silver, with what appears to be the typical Cannonball color (not sure if it's orange, green or what with my defective eyes) on the thighs, shoulders and upper arms. Head looks like Cybertron cannonball (I.e. Cybertron red alert) with typical visor and mouth.
This still seems not to explain the alternate head found in the Ratchet instructions, pictured below.

Additionally, Jesse Wittenrich, writer of last year and this year's magazine comic, explained their choice of the mold at fellow fansite AllSpark.com:
The very first toy explored for Cannonball was Breakdown. Because on the face of it, it seems perfect.
But after playing around with the transformation, how that related to the deco, the mold layout, and the exaggerated proportions (tiny head is tiny!), it didn't really work. Ratchet was actually the third option explored, but the robot mode was just perfect for him. Vehicle mode coincidentally became another emergency vehicle which some fans may like...and others not so much.