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Big Wind - The most powerful fire engine of the world: 2 MIG-21 jet engines mounted on a T-34 tank base
(media.techeblog.com)
It's for extinguishing oil well fires, owned and developed by MOL, the Hungarian oil conglomerate. It was used in Kuwait after the Kuwait-Iraq war, here is a video of it in action: https://www.youtube.com/watch?v=uyGDxglTVgA
It's still in use and maintained, the base was replaced with newer tank recently, as it was hard to find replacement parts for such an old model.
Video from some years ago, timestamped, there is a lot of Hungarian narration before that point: https://youtu.be/YYF8YQ7pLng?feature=shared&t=494
Good article in English about this beast, with a lot more images: https://www.autoevolution.com/news/a-firefighter-s-dream-meet-big-wind-a-tank-with-jet-engines-that-s-a-fire-truck-185011.html#
I saw this thing work in the documentary about the Kuwaiti oil fires the first time I ever went to an IMAX theatre. For some reason that has stuck in my mind for nearly 30 years.