Installation 04v2

Installation 04v2 was a unfinished replacement of Installation 04. Intended to directly replace the original, it was released from The Ark after the destruction of the original. During the Battle for The Ark, the UNSC and it's Elite allies shortly used the Activation Index Cortana had kept from the original to activate the ring near the Ark, planning to eradicate the Gravemind's Flood army which had came there following the Covenant's plan to activate The Array within the Milky Way Galaxy. This plan successfully stopped the active Flood threat, ending the war.

Production Notes
Canonically the Installation was not given a designation, and was simply referred to as "Halo" or "Replacement ring" within Halo 3. However, within the games files there are unused hints to help players find and unlock the Skulls hidden throughout the missions, with the unused hint for the Mythic skull hidden on the mission taking place on the ring reading: "Interred on Installation 04v2.". While this was officially unused, It is the only known designator to be used at any point by Bungie, and also given how late this cut seemed to be, it is evidently what the designation was internally.

In Modern Canon
343 Industries's first publication, The 2009 Halo Encyclopedia (2009), listed the ring as: "Installation 04B". This was the first official canonical designation, and notably close to Bungie's internal name. It has been said that this name, like many information included in the release, was actually taken from the fan run wiki Halopedia. However, this claim is unverified, and the history for the ring's page named it was named: "Installation 04 (II)" and "replacement for Installation 04". It can actually be found that a user had to correct the name after the Encyclopedias publication, which rather clearly indicates this was seemingly just a unverified false myth.

In 2017's Halo Wars 2, The UNSC returns to the Ark and discovers that "the Ark keeps an almost-finished ring in the central forges at all times.", as an emergency replacement for any destroyed rings. This notably conflicts what was established in Halo 3, where Installation 04v2 was visibly not "almost finished", and in this very early and incomplete state its firing was said to be so destructive that it "shook itself to pieces" and "did a number on the Ark.". .

This new information also contradicts what was clearly implied in Halo 3, where Installation 04v2's construction was clearly only started after the destruction of Installation 04. Unlike the new replacement ring as seen in Halo Wars 2, Installation 04v2's design and layout of the ring was nearly identical to the original, as evidenced by the almost identical architecture of the Control Room and it's surrounding area, and the island with the Silent Cartographer being present in an early stage. Installation 04's Activation Index was able to be used to activate 04v2, and 343 Guilty Spark immediately reinstated his post as the replacement rings Monitor. The apparent intention that the installations were made with a intended design in mind, and that upon an installations destruction it will reuse that design for the replacement, where it would be sent out to the original location as a new version of the same ring. This is further evidenced by cut content, with the unused internal name being clear of this, and in an earlier version of the ring's reveal cinematic it's said that "(The Ark) detected the loss of Installation 04, and began construction of the replacement immediately.".

During this time it was also made clear by 343 employees that the rings canon designation "04B" (similar to "04v2") was no longer official. It was being established that the number was order the ring was manufactured, and going forward meant that the ring was now retconned to be "Installation 08". It was said that the new rings were not actually meant to directly replace the original, but to cover the same part of the galaxy where it was. The name "Alpha Halo" was now meant to be used as the shared term between the replacement rings, denoting the firing position. This explanation is clearly meant to be continuing the implication in Halo Wars 2, where the new ring was actually a new design unrelated to the original, constructed as an emergency back-up for any of the rings. This new canon has had a mixed reception, with some fans preferring the idea of "new" rings, and other fans pointing out that this is very contradictory of what was previously established and implied in Halo 3, preferring the original version.