The cab transforms into the robot mode of Optimus Prime himself, with the addition of a pair of removable blue fists that plug into his headlights.The fists themselves do not store anywhere in vehicle mode, but can fit easily in Prime's opening chest compartment (originally designed to accommodate two Diaclone driver figures).
Prime's trailer opens up into his Combat Deck, containing the scout drone, Roller.Since 1984, Generation 1 Optimus Prime has received the largest number of toys for any single Transformers character, a testament to the character's enduring popularity and status as a hero to many fans.The original Optimus Prime toy started life as the Diaclone toy, "Battle Convoy", created by a team of Takara designers who came on board when the original designer fell behind.This team included Hiroyuki Obara (listed as the sole creator on the toy's patent) and famed mecha designer Shōji Kawamori.The toy transforms into two major components; the first component being a red and blue post-1973 White Freightliner 96-inch cab WFT cab over engine semi-trailer truck partially composed of die-cast metal, and the second component being a large silver trailer of currently-undetermined model.The interior space of the trailer allows storage room for one standard Autobot car, which can also be shot forward by the launcher.
Optimus Prime was subject to several molding and color variations in his early days.
The earliest release of the figure featured larger fists, a gun with a thick, round barrel, a slightly-differently shaped gas pump, grey rockets, a grey Roller, a grey launcher in his Combat Deck, and metal plates in the floor of the Combat Deck (a holdover from the Diaclone version of the toy, to which the magnetic feet of the pilots could cling).
The interior of the Combat Deck features three pegs that can accommodate Prime's laser rifle, fuel pump and nozzle accessories, and seating for two Diaclone drivers.
As its central feature, the Combat Deck features a missile-armed repair drone pod mounted upon a boom lift arm (featuring another cockpit for a Diaclone driver), which can also be extended through holes in the trailer's roof and front-end when it is closed.
Situated in the base of the boom arm is a spring-loaded launcher that can launch Roller out of the Combat Deck and into action.
Roller himself has seating for four Diaclone passengers, and features a port that can accommodate either Prime's rifle or the fuel pump.