One of my favorite TFs was G1 Downshift. You could get him via mailorder, saving up Robot Points and sending them and five bucks to Hasbro and they'd mail you a figure they figured they couldn't sell in a package.
The Omnibots (those mailaway figures) are a little smaller than the regular G1 cars save for Skids (misconception about Skids: he's a minivan. Us Americans had seen compact cars, but not the City Turbo.). Yet Downshift, Overdrive, and Camshaft all had "battlemodes," where a part of the car flipped out and a weapon could be displayed. The appeal of Overdrive, already a red sports car, he had WINGS that flipped out, so that made him one of the first Triple Changers (well, along with Tracks) even though neither is designated as such. I had Overdrive and Downshift; I wouldn't get Camshaft until literally a year ago when I was full on collecting and realized "Hey, I don't have the 3rd mail away Omnibot."
I thought Overdrive was pretty cool but, looking at him now, he's kind of a flimsy bot. Or Flimsybot (tm). Somehow he stayed together over the years, but I lost two of his three weapons. When I got Camshaft out of the need for completion, well, I was disappointed. He was a little hard to transform, and honestly didn't look that cool as a robot. Plus his head pops up and doesn't stay up; I had to rest it against the missile in the launcher directly behind his head.
Downshift was always a solid figure compared to the other two, and I don't think he gets the love he deserves. His transformation is not unlike that of G1 Wheeljack, and his hands can actually hold things!
This gave me an idea for a custom, of course. And a theoretically easy one...
Now, if you've seen my customs, they're a little on the wrong side of how to do things. I just slap some paint on a figure and maybe the paint holds after a few coats before I put a gloss 'enamel' to keep that paint on. I did the Paul Stanley Prime as a joke. I made my own versions of "Clamp Down" and "Deep Cover" and there is debate if I should have ruined two perfectly good Generations Red Alerts.
Generations Wheeljack and set to painting. I had to apply a LOT of white. I used acrylic. I used a lot of white paint. FOR THE HEAD, I got an Armada Deluxe Optimus Prime. NOW, here's the thing: most Generations and Animated figures seem to have neck/head joints that are comparatively the same size. I'm making a guess here. Generation Wheeljack's neck ball joint is larger than most other figures from the Generations line. The Armada Prime head could fit on a Classics Sunstreaker or, well, most other, but I had to drill the head opening and open it up before it would fit on the ball joint and stay on, and still turn. Then I cut or shaved off the points on the side of his head. The biggest disparity I think is that G1 Downshift's head is a square, and practically that of a Scramble City combiner figure. Even though the cartoon and later models are a little more rectangular, Prime's head was definitely rounder. Hopefully y'all give me a break on that. ALSO, I was trying to be delicate while painting his head, and didn't want to ruin the eyes, so there's a bit of blue I didn't paint over. :S