History Denver Heads ?

I just bought a set of Ford 24 bolt aluminum heads at a swapmeet in Altamont, Il.
I have seen Ford Denver heads and my recollection is that there were cast similar to cast iron heads externally.
These are rather square shaped and flat across the head surface. The plugs are 18 mm.
I have done a search in HAMB files and read about variations of Ford, Canadian and other cheater heads.
These seem to have no marking. Any knowledge of this style or of history of these particular heads would be appreciated.
Thanks
dechrome

 

Kind of looks like a Thickston head.
Appears to have bosses for the finned covers.

 

Note what Bruce Lancaster said about Denver heads in this Fordbarn thread:
https://www.fordbarn.com/forum/showthread.php?t=69804&showall=1

 

I second them as being Thickstun, they would have a finned cover held on with one bolt which threads into that center boss cast into the head. The Thickston logo appears to be missing however.

 

Thanks for the replies. These do look like Thickstun heads. A further look appears that a logo may have been removed.
Thanks
dechrome

 

Hope you don't have trouble getting those old plugs out of there!

 

Could have been Used as "cheater" heads?

Sent from my SM-G550T using The H.A.M.B. mobile app

 

An update on the Thickstun heads that I recently purchased. The plugs did come out and threads cleaned with a 18 mm tap. the gasket surface cleaned up on surface grinder and the corrosion cleaned with a plastic bristle rotary brush.
This came from HF and is one product that worked. Surface corrosion was quickly cleaned without marking the aluminum, including plug pockets and valve pockets.
dechrome

 

They look like they've been milled a lot. Not much dome left.