The Crusty Legs is a massive pilot-operated tank developed by an unknown Eastern country. It is similar to the Samurai Tanks and Kagura's samurai mech in that humans operate the machinery. It first made its debut on the game's event titled 'Task Force 8th', where it was also a playable unit.
"A huge multi-legged tank developed in an Eastern country. It is mechanical in appearance, but is actually powered by humans. The funcionality of its human-powered secret weapon, the Flame Tornado Quadruped, baffles scientists."
- ~Metal Slug Attack in-game description.
In Metal Slug Attack's event, the Crusty Legs was the featured unit of Task Force 8th's Task Force Box Crank. It is a massive contraption that moves slowly towards the enemy. When it spots the enemy, it fires two salvos of cannonballs and shots - each salvo consisting of two rolling balls and standard shots. Although the balls move slowly at first, their speed picks up greatly upon stabilizing. The rolling balls appear to be improved from the Nop-03 Sarubia, dealing significant damage to any enemy they make contact with, although they can be easily destroyed. Enemies too close to the Crusty Legs will get stomped by its front feet instead.
As its special attack, the Crusty Legs will power up its Flame Tornado Quadruped, levitating mid-air while the base of its feet ignite and generate flames, before charging towards the enemy to burn them. The attack can be stopped after a prolonged duration or if it takes too much damage in this state. While the flamethrowers are active, the Crusty Legs will replace its special attack by firing a flaming shot from all three of its cannons.
Despite its bulky appearance and slow movement, the Crusty Legs are quite mobile, possessing the ability to evade enemy attacks. If the flamethrowers are not active, it simply jumps in place; if the flamethrowers are active, then it staggers backwards slightly to avoid the incoming attack.