more help identifying oil cooler fitting types please

[MoreWellie]

I measure it at 16 tpi and a diameter of .775 inch (19.7mm) which is quite close to 3/4 UNF but the diameter for that should be 0.75 inch (as the name implies)
the unit is a land rover oil cooler but standard pipes are not an option as it will be used for something else
From the ledge I am assuming it will be an o ring type

 

[Rannsachair]

I measure it at 16 tpi and a diameter of .775 inch (19.7mm) which is quite close to 3/4 UNF but the diameter for that should be 0.75 inch (as the name implies)
the unit is a land rover oil cooler but standard pipes are not an option as it will be used for something else
From the ledge I am assuming it will be an o ring type
View attachment 254396

Likely M20 x 1.5?
This may be handy: https://www.apexfluid.co.uk/technical/thread-id.php#orfs-thread

 

[MoreWellie]

@Rannsachair Yes thank you, I have checked the thread and it matches a 1.5 thread checker so my 16 tpi should have been 17