No holographic rubsign on cab - hence, pre-rub. Only newly releases of Optimus Prime come with the rubsign.
Accessories such as the laser blaster (gun), fists, gas pump and nozzle are larger and more detailed than the "Standard" Optimus Prime's - hence, the Bloated nickname.
Still trying to locate one with the nice-conditioned box but for now, this loose piece would have to suffice...also listed out are the variations or differences not found on the "Standard" Optimus...
Notice the conspicuous metal plate tabs on the trailer?
If you look closer, you'll find that the circular design top left of the insignia has 6 gaps while the octagonal design in the bottom front corner of the trailer has a series of horizontal lines.
All the fine details of the trailer door (rectangles, handle, rivets, even the holes at the top of door) are different.
The intricate detailing along the inside walls of the trailer are comprised of metal plates with ink and paint images printed on them and each held in place by six plastic tabs.
Everything's grey - roller, missiles and entire launcher.
"Bloated" accessories - check out the enlarged gun and fists.
Rare...1980, 1982 Takara, imprinted at the bottom of the trailer.
Pre-rub...no rubsign. Even the hole for the screw that holds Optimus Prime's head in place is small and shallow.
Headlights have larger diameter holes for the fist pegs. Look closer to notice that the lines on the truck grill are thinner.
Optimus Prime packs a punch!! Just look at my fists!!
Had some help *shy* identifying the differences...credit to tfw2005. For the complete guide, please refer to Bloated Fist vs Standard Optimus Prime. The site has been my one-stop knowledge centre so far...