Grot Tanks
Grot tanks are what happens when a bunch of gretchen have too many spare parts and not enough supervision. These ramshackle "tanks" are quite literally piles of scrap barely held together with duct tape and hope, and like a lot of ork technology, they're somehow still effective. Their armor might as well be tissue paper, being as light as a vehicle can be, but the sheer stupidity of their design means that any given hit might just blow off some redundant junk rather than causing any real effect. Grot tanks are armor 10 all around, but because of this scrap they get a 5++ save. Unfortunately, their engines are just as trash as their armor. Grot tanks have a random movement that might be as slow as two inches, so they don't reliably go where you need them. The few weapons they manage to attach to these junk piles aren't exactly worthy of the name 'tank'. A single big shoota, rocket launcha, or other ork heavy weapon is all they get. Still, they're dirt cheap and have BS3, giving them some potential to be an effective fighting force.
Grot Megatank
More like a rolling mini battleship, and can be scratch built from one. The grot megatank is like five grot tanks smuched together into one large gretchen ran monstrosity. Five turrets, three of which are twinlinked and each of which can independently target foes... it's got some interesting tactical flexibility. Again though, it's weapon choices are limited to pretty much what you can put on a killa kan, with some extra explosive barrel options with funky rules for shooting.