There are 4 Boxcars with roof hatches in this 1935 Alma view
Of course you can't hear me chuckling over this...
The information appears two places in Vol. VIII page 11 and page 211. Again as mentioned above Stan Schewdlers pointed out a photo (page 41 Vol. VIII) and asked what I knew about the hatches. Well that started the search and eventually I found 8 numbers. Where? In piles and piles of photographs. I don't know if these 8 were all of them and I never found any description of their use. This has been a matter of deduction such as we've touched on.
Late 30's view of Blackhawk with Boxcar 8281 with roof hatches plus 8283 without. R. Kindig
Harry's article was written after I shared what I knew with him. When I operated that obscure little one-horse parts business "the C&S Connection" I made white metal castings of these in O scale. They had one large hinge on them.
If you check out pages 183 and 184 of Rail Annual 12 you will find where I got the details of the text you quoted (and note that I credit my sources including Stan and Rail Annual 12 on page 18). On page 211 are the charts I developed for quick reference to understanding (more or less) C&S Freight Rolling Stock.
Your quote of the text and chart caught me off guard when you said it was Rail Annual 12 because I didn't recall reading anything about the cars in any publication - had it been so long I'd forgotten? Ya sent me into a frenzied index trekking episode!
Also on page 184 is a brief description of drop end coal cars numbered 4600 - 4614 built from other coal types. That is a nugget I've intended to chase down for years - and frankly forgot about as well.