I'm kind of surprised no one has thought of or attempted this yet, but IDW Devastator with the following specs:
numbers (#) before a body part designates which regular configuration this body part is for (there are three "regular" configs, but people who have this custom could easily mix and match a bit)
This is the normal/expected section body parts thing:
Mixmaster: Leg
(1) Scrapper: Leg
Long Haul: Lower Torso (and a bit of upper torso(?))
Bonecrusher: Arm
Scavenger: Arm

then it gets weird/cool:
Hook: (1) upper torso and head OR (2/3)leg
(2) Prowl: upper torso and head
(3) Megatron: upper torso and head

With all figs fully transformable (Robot, Vehicle, and body parts) and with Generations level articulation and not looking like abominations of nature i.e. be shellformers or partsformers or have huge scoops between their legs (IDW G1 Devastator, not Michael Bay Devastator). Preferably the figures would be roughly deluxe sized, but with thee complexity they might end up larger or smaller. Devastator shouldn't be a brick either (as poseable as Metroplex in terms of limbs, (but I'm not thinking like articulated pupils or any of that craziness.) and be fairly well proportioned (not leaning to the side, balanced, not having one arm drag on the ground while the other doesn't make it all the way down to Long Haul). Devastator should also, in my opinion, be as self-contained as possible in his components, or at least have his kibble be weapons and stuff for them (Chest shield as jet pack or shield, for example).

Well, that's my idea. I'd post it as a request, but my funds couldn't afford a custom of this size and quality (recently bought a Generations Titan-Class Metroplex)

 

I'm surprised a 3rd party hasn't made a Hook and Prowl that can be added onto Hercules or Giant. Just make a hook that can be a leg, and a prowl that can be the head.