Artist Guido Guidi has posted a few pieces of concept art from his time on Transformers Ongoing as well as the line art of issue #19 to his
deviantART page. We get to see Starscream and Skywarp in the hybrid F-22/F-15 form that was used for Thundercracker in issues #10-12, a character study of Optimus Prime based on Don Figueroa redesign, and concept art for Sunstreaker's pet insecticon Bob. Bob was originally going to be called Spike, but his name was changed to avoid confusion with the human character. The concept images are mirrored below, to see line art from Transformers Ongoing #19 and more of Guidi's work click
here.