M51 or M-51 may refer to:
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M-51 (Michigan highway), a state highway in Michigan
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M51 highway (Russia)
The Russian route R254 is a federal highway in Russia and Kazakhstan and is part of the Baikal Highway (which is part of the Trans-Siberian Highway). It runs from Chelyabinsk through Kurgan, Petropavl, and Omsk until Novosibirsk, with a total lengt ...
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M51 (Cape Town)
The City of Cape Town (Cape Town metropolitan area) like most South African metropolitan areas, uses Metropolitan or "M" routes for important intra-city routes, a layer below National (N) roads and Regional (R) roads. Each city's M roads are ind ...
, a Metropolitan Route in Cape Town, South Africa
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M51 Skysweeper, an anti-aircraft gun
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M51 MACI mine
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M51 SLBM, a French nuclear ballistic missile
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BMW M51, a 1991 straight-6 Diesel engine
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Sherman M-51, an Israeli modification of American M4 Sherman tank
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Eidgenössischer Stutzer 1851, a historical service rifle of the Swiss Army
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Messier 51, a spiral galaxy also known as the Whirlpool Galaxy
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Samsung Galaxy M51, a smartphone released in 2020
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