With a proliferation of mobile suits on the modern battlefield, the North American Republic needed a platform able to engage at medium to long range as a fire support unit. It had to be mobile enough to stay within effective range of the front line.
The RX-77D Guncannon was the result of Northrop-Grumman's development for just such a fire support mobile suit. Equipped with dual-linked 20mm cannons and dual 10mm machine guns, it has a formidable arsenal without even picking up a hand articulated weapon.
Building instructions are not currently available.