Earth-120185
Within the multiverse of Marvel Comics, each iteration of Earth is given a numerical designation that serves to represent that universe. Earth-120185 is the universe in which the UK-published incarnation of the Transformers comic book series occurred. At its core, the sequence of events involving the Transformers in this reality is largely similar to that of the reality chronicled in the US-published comic, "Earth-91274", sometimes known as "Earth-Transformers".
All except one of the Transformers-related incidents from Earth-Transformers also occurred in Earth-120185. Changes in these events are largely confined to variations in dialogue and the presence of differing peripheral characters.
Significant divergences usually took the form of additional events not recorded in Earth-Transformers. These regularly involved time travel, and were often directly connected with the minor changes in the shared events. Note, however, that a version of at least one of these incidents also happened on Earth-Transformers, without being recorded fully in the chronicles of that reality.
The most notable Transformers-related omission from Earth-120185 is the encounter with G.I. Joe that occurred on Earth-Transformers. Reflecting the close parallels between these two realities, the Autobot Bumblebee was still destroyed and reformatted into Goldbug, but this was a result of time-travel events, rather than the incident with G.I. Joe.
The absence of these events reflects the fact that the history of G.I. Joe is very different on Earth-120185, far more so than that of the Transformers. Here, the G.I. Joe team is the U.S. section of an international task-force code-named Action Force, and the versions of personnel like Flint and Dusty in this reality are non-American. Moreover, the chronology of G.I. Joe's operations is very different on Earth-120185. Events which occurred on Earth-Transformers before the revival of the Cybertronians aboard the Ark occurred in this reality after the apparent deaths of Optimus Prime and Megatron.
The essential difference between Earth-120185 and other universes in the Marvel Multiverse is that it became the battleground for the war between the Autobots and Decepticons. There are some elements that exist in some form (although not exactly the same form) across both Earth-120185 and the mainstream Marvel Universe (Earth-616). Many of these, such as Spider-Man, Reed Richards, Nick Fury, Dum Dum, (presumably) Godzilla, the Savage Land, U.S. 1 and Dazzler, are also found on Earth-Transformers, but some are not explicitly recorded there, such as Doctor Doom, who once clashed with Earth-120185 inhabitant Combat Colin. For unknown reasons, these beings did not factor into the later stages of the Transformers' war.
Per the original state of its timeline, the 21st century of Earth-120185 saw Unicron attack Cybertron in 2006. Following Unicron's defeat, the Galvatron of this era travelled back in time to 1987 and remained there for two years, ultimately resulting in a rift in the fabric of space and time that destabilised the universe. Although this rift was eventually sealed, Earth-120185's timeline was left permanently altered, its future warped into a dark shadow of its former self and diverged off from the primary timeline, becoming an alternate universe of its own.
It is unclear whether or not the adventures of the Autobot Earthforce take place on Earth-120185, or a further divergent Earth.
Notes
Earth-120185 was given its name in the 2006 edition of the Official Handbook of the Marvel Universe, in the profile for Death's Head. It derives its name from January 12th 1985, the publication date of "Man of Iron", Part 1, the first UK-originated comic. (If we were to determine the name for this universal stream using the Transformers classification system, it would almost certainly be Primax 185.12 Gamma.)
The variations in UK continuity before the first time travel story were mainly additions rather than explicit alterations. Most actual changes to the reprints, such as the adjustments in Grimlock's dialogue and the occasional reordering of scenes within a story to make for better cliffhangers when U.S. issues were split in two, could be explained as the results of editing and translation. At first sight, it might seem that the major divergence between the two realities was a result of time-travel. This would also tie in with the fact that the U.S. story explaining Bumblebee's reformatting as Goldbug was replaced by a further time-travel story.
Unfortunately, when the UK reprints of the G.I. Joe comic began in 1987, the decision was taken to use U.S. stories from 1984, which provided important backstory for the later strips. The "Ancient Relics!" crossover then established that these re-dated stories were part of the current Transformers continuity of Earth-120185. This caused a major continuity discrepancy with Earth-Transformers, as the American G.I. Joe and the Transformers crossover indirectly established that these events had already happened there, at the time of their original publication in U.S. Marvel comics.
Thus, by the time the Transformers were revived aboard the Ark, the continuities of the two realities had already diverged more significantly than was apparent from the Transformers stories at this time.
In fact, the chronological discrepancy between Earth-120185 and U.S. continuity appears to date back at least four million years, to the time of Shockwave's arrival in pursuit of the Ark. On Earth-120185, he left the Decepticon space cruiser cloaked in orbit, where it was shot down by Galvatron in "Target: 2006". On Earth-Transformers, the ship was instead hidden underwater, and eventually became Shockwave's base near Blackpool. Appropriately, the first (er, only) scene featuring the un-destroyed Decepticon ship in "Surrender!" occurs at the exact point at which the U.S. comics continuity becomes completely irreconcilable with the UK version. (In the Earthforce story "Bugged!" Shockwave's base was also shown to be a spaceship parked underwater.)
On the other hand... if we could wiggle the G.I. Joe discrepancies, maybe the healing of the temporal rift in "Time Wars" brought the Earth-120185 continuity into synch with the U.S. storyline, or something? But that still wouldn't explain Earthforce....
