Their website is pretty abysmal, and doesn't keep up to date coverage with their current issues (Motor Trend sells e-subscriptions to all its publications, so they don't want anything out there free), but the new Truck Trend out on shelves now has a cover article on the truck used as Ironhide in the movie. I wish I could give you pics of the cover, but someone'll have to buy it and take one. They don't show any pics inside of robot Ironhide (just some stock footage everyone's seen already of others), but they do have quite a lot of info about modifications to the truck itself- such as them keeping the engine stock for fear of reliability issues, although they did relocate the battery box. They also put massively offset wheels in the back (most Topkicks are duallies, Ironhide only has four wheels), heavy Road Guard bumpers front and back as well as other mods. GM donated two Topkicks to the production so filming could be done simultaneously in different locations.