Classic Prime's arm kibble always drove me crazy. Any other character I wouldn't have minded it, but it just didn't seem very Prime-like to me. I waited years for someone more skilled in kitbashing to than me to find a way to do this, but I finally just broke down and did it myself. Basically I've just shifted the kibble to a big backpack, but it's less noticeable there. The airfoil also merges with it fairly well. No partsforming necessary. The sides of the cab are only held on by friction, as I didn't want to risk attaching anything to the brittle chrome, but they stay on unless you actively remove them. Most of the modding is accomplished from a piece of Cybertron Crosswise, which fits almost perfectly in the open space left behind Prime's grill. I had to cut the piece of Crosswise and parts of Prime's body to get it to work all the way, but I was astonished how well everything fit. That little peg on the Crosswise piece holds the front of the cab together in both modes, so it's fairly tight. The loosest piece is where it goes into Prime's back, but even that could be tight if I had cut it better. I didn't worry too much about making the cleanest cuts, partially because the modded parts are only visible during transformation, but mostly just because I'm lazy and impatient. Vehicle mode's mostly unaffected. The only changes are that there's a slightly larger-than-normal gap where the front of the cab lines up with the back, and the folding Crosswise piece sticks down a little too far and slightly touches the ground. Both of these could be fixed with some more sanding, but certain areas were getting kind of thin and I didn't want to risk something breaking.