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So i just found 1 of my old hdd's from a Laptop i sold in 2017.
Now i wanted to check for some lost pictures or something else but i never recovered a old hdd with a other os.
99,9% sure its Win8.1 on the HDD but running Win10 on the other Notebook.
Do i need other tools for this?

[Xycon]

You should just be able to hook it up by USB using a regular HDD dock or something and be able to plain access it.

[Cocaine]

You should be able to just connect it to the pc without tools.

[Aeowulf]

Try connecting it as an external. If it is unable to be read, use Recuva on it.