You're right, here it is. I was trying to look for that post as well but couldn't find it, thinking that it was a distinctly different third party company that was offering it.
IDW-esque tank treads are there, but I didn't like the original head/shoulder proportions. The original head seemed bigger (now we know he was meant to be a Headmaster all along) and the way that it sunk into his chest/shoulders seems to reduce the level of bravado they were trying to achieve.
I agree with kup, that the head-mode excludes non-G1 Fort Max owners, but that didn't necessarily stop me from enjoying BW/BM/RID Megabolt Megatron ;)