18pr HE markings

[Burney Davis]

I have this early 18pr HE which looks to be of standard construction. It does not have a mark number but has 'D22004D' where the mark would normally appear.

Is this a reference to a design number? Any help or thoughts appreciated.

 

[Snufkin]

It is the Design/Drawing number. List of Changes paragraph 17302 refers:

 

[Burney Davis]

Thanks again my friend. Nice to know i was on the right track, but I'm used to seeing the reference as DDL.