The Assault Frigate line hails back to the Clone Wars when Rendili StarDrive endeavored to upgrade the aging Dreadnaughts into newer warships. The third entry to the Assault Frigate line, the Assault Frigate Mark III was introduced to the New Republic's fleets to replace their aging Mark I and Mark II predecessors. Now the Mark IIIs get to do it once again!' - Lando Calrissian commenting on the Assault Frigate Mark III 'The Empire was foolish to pass on the Mark IIs, and they got to see these beauties contribute to their defeat.
The image was acquired through Star Wars: Empire At War - Forces of Corruption using the Rise of the Mandalorians mod Beta. Note: The information below is from my own universe which is a blend of old and new canon and is not to be considered canon in any other universe but mine.
This is one of the vehicles from my canceled Star Wars Fanfiction Series: Star Wars: The Shadow Wars.