1940WLDR Head identification

[servi47car]

Hi,
Can anyone help me identify the heads on my 40WLDR?
The markings are unlike any I have seen and my research came up empty.
Thank you

[Rubone]

'48 up WR heads.

[kitabel]

Note that these are pop-up, and should only be used with late WR or K model pistons.