I have been asked to find plans and design information on this item. The 520 Battle Platform. Here is what we know so far.
https://vignette.wikia.nocookie.net/starwars/images/4/40/Gargantuantank.jpg/revision/latest/thumbnail-down/width/732/height/331?cb=20071229231706
The 520 Battle Platform was a heavily-armored and shielded battle platform prototype that was originally designed by Aratech. The 520 was equipped with powerful laser cannons and strong shield generators. Two turbolasers located on the front and back were capable of penetrating heavily armored vehicles, such as the AT-AT walkers used by the Galactic Empire. Four anti-infantry laser cannons protected the battle platform against infantry-based attacks; however, it had no anti-air defenses. Because it was a prototype design, only one such vehicle was ever made. This model was eventually stolen by Garm Bel Iblis, who gave it the designation Gargantuan and used it during the Galactic Civil War to aid the Rebel Alliance.
https://vignette.wikia.nocookie.net/starwars/images/4/40/Gargantuantank.jpg/revision/latest/thumbnail-down/width/732/height/331?cb=20071229231706
The 520 Battle Platform was a heavily-armored and shielded battle platform prototype that was originally designed by Aratech. The 520 was equipped with powerful laser cannons and strong shield generators. Two turbolasers located on the front and back were capable of penetrating heavily armored vehicles, such as the AT-AT walkers used by the Galactic Empire. Four anti-infantry laser cannons protected the battle platform against infantry-based attacks; however, it had no anti-air defenses. Because it was a prototype design, only one such vehicle was ever made. This model was eventually stolen by Garm Bel Iblis, who gave it the designation Gargantuan and used it during the Galactic Civil War to aid the Rebel Alliance.