since Palladium has seen fit to alter The Sentinels mecha for no discernible reason other than "because", there has to be some explanation for the mecha that were planned for The Sentinels and have appeared in canon animation and comics. So, since they are no longer REF Destroids, I suggest we make lemons into lemonade and go back to a little line in The Masters War and REF Marines Sourcebooks:
Earth is left under the protection of The Army of the Southern Cross and what is left of the United Earth Defense Force.
Its a verifiable fact that we see a MAC III in Robotech: Love, Live, Alive on Earth during the evacuation following The Invid Invasion. We see cannons, that are in the same configuration as the MAC III, firing what appear to be shells in Half Moon. So, why are these mecha not in the REF Marines Sourcebook? Why, they're not REF mecha obviously! They're UEDF mecha and remained on Earth until following The Invid Invasion.
So, I present to you the UEDF Battloids (and I use that term because that is the term listed in The Sentinels Script Books 1 & 2 and Robotech Art 3).
CBH-2 Excaliber
CBM-2 Shark
CBA-2 Raider Mk.1
CBA-2 Raider Mk.2
CBL-3 Gladiator
MAC II Thundercracker
The missiles carried by the Excaliber, Shark and MAC II are all medium range (300mm Prowler). The Thundercracker should have the same gauss cannons as the REF's Monster Mk.III, but carry a larger capacity (more internal storage). It should also have x2 Prowler Missile Pods in each weapons arm (the lineart shows exhaust ports in the back). The Raider Mk.1 has slugthrowing gatling cannons, while the Mk.2 are lasers.
These Battloids probably started off fighting during the early days of The Malcontent Uprisings and were the first new Earth mecha to roll of the assembly lines of Space Station Liberty. They were eventually superseded by the newer Battloids used by The Army of the Southern Cross and assumed a secondary/support position during The Second Robotech War.
Edit: Considering the metric crapload of material left OUT of both the New Generation AND REF Marines Sourcebook, I decided that I would go ahead and list all the remaining vehicles/etc as being UEDF. Eventually, it would be superseded by the Earth Reclamation Force. I'll start on that later....
Edit 2: Just noticed I made a goof. What was called the MAC III in the old RPG is actually listed repeatedly in sources as the MAC II, so I switched it. This will make sense as neither the Thundercracker nor the Tiger (when I get around to it) are listed as Heavy Weapons Robots, but as Mobile Assault Cannons instead. The term Destroid is also abandoned for everything but The Macross Saga and REF Marines mecha in question.