These are valve guide inserts. It's impossible to know what they fit without exact measurements of the bore and diameter. There are literally thousands of different sizes and thousands of different applications. Since you show 12 of these the best I can say is these are for a 6 cylinder engine assuming 2 valves per cylinder. The URL shows one very similar in design to yours but there are many different types made from different materials.

These are valve guide inserts. It's impossible to know what they fit without exact measurements of the bore and diameter. There are literally thousands of different sizes and thousands of different applications. Since you show 12 of these the best I can say is these are for a 6 cylinder engine assuming 2 valves per cylinder. The URL shows one very similar in design to yours but there are many different types made from different materials.

References:

https://dieselpro.com/detroit-diesel-5129919-valve-guide-series-71-92.html

Those are cylinder head valve guides. You will need to make more measurements regarding inside diameter and outside diameter to make a match as there are millions of valve guides in the world.

References:

https://www.jpcycles.com/product/723-732/kibblewhite-cast-iron-001-exhaust-va...

Reason:
Another opinion was accepted instead.