Junka
Junkas are essentially the catch-all term for any vehicle created by Orks from the remains of completely destroyed vehicles; often looking more like a Frankenstein of a vehicle with different vehicle body parts stitched or glued together. They take on a entirely new level of looting as looted vehicles often comes from enemy vehicles that still functions and are given the proper Orky treatment.
Most Junkas are completely unique and no two look alike due to their mishmash of different vehicles. Even by Ork standards Junkas are difficult to independently classify from their usage. So far there are only two identifiable types of Junkas documented by the Imperium. The Junka Trukk and the Mekboy Junka.
Junka Trukk
Junka Trukks are made from Feral Orks, which is usually to compensate for their overall lack of advance technology. It's not uncommon for Feral Ork tribes to salvage vehicles left by other forces. These vehicles will usually have been heavily damaged, and it is rare that a Feral Ork tribe will either have the mechanical expertise or spare parts needed to repair them correctly. But that generally does not stop the Tribes from cobbling things together with their boilers and boars to make surprisingly effective war machines. Junka Trukks rely on their speed to overcome their relatively light and poor quality armor.
Think of them as the poor man's Trukk and like most Ork vehicles they are highly customizable. The Junka Truck usually features a single pintle-mounted Big Shoota that is operated by a dedicated gunner, but can swap it with a Rokkit Launcha for anti-vehicular or a Burna for anti-infantry purposes. The vehicle is crewed by an Ork Gretchin, who drives the vehicle, and a single Ork, who can be a Nob or a Wildboy. The vehicle is also open-topped, allowing the passenger to be armed with Shootas or a Shoota and a Choppa, so that the Ork is able fight off enemies at close range. Junkas also double as inefficient transports, with its passengers riding into battle clinging to any spare piece of their technological masterpiece in large numbers. The Junka Trukk can also be outfitted with many types of attachments and upgrades, including armoured plating, a big grabber, a boarding plank, a bolted-on Big Shoota, a reinforced ram, a Stikkbomb chucka, or a wrecker ball.
Mekboy Junka
On the other end of the spectrum, Mekboy Junkas are used by...well...Mekboyz and are often seen as the more advanced and sophisticated of the two (By Ork standards of course). Often these vehicles are a way for younger Mekboyz to showcase their skill and talent in building vehicles and weaponry, hopefully impressing Warbosses and Nobz. Think of them as the Ork equivalent of a Children's Science Fair.
Like the Junkas used by the more primitive brethren. Mekboy Junkas are sometimes scratch built or looted, but usually are a ramshackle cross of both. Like many Ork vehicles, each Junka is unique, incorporating the Mekboy's own special 'innovashuns'.
Mekboy Junkas come usually with a Deathrolla, a turreted Big Shoota and two side mounted Scorchas which can be replaced with Rokkit Launchas or more Shootas. Like all Junkas, Mekboy Junkas are fast, very fast.