Randy Hammill responds:
***** Those look like Improved Dreadnaught Ends for 10’0” IH cars. They have been described as having rolling pin shaped corrugations and a stiffening rib at the top. *****
***** GN 11375-11874, 18000-20499
Well . . . . . not so fast.
Referring to Ed Hawkins work again (also included in RPC vol 8), the ends in the pictures are 4/3 ends, with _N. Hawkins defines these as IDN Type, or IDN-1, with no top stiffener.
The GN series you mentioned (along with another approximately 16,000 cars for other roads) use the IDN-1 ends.
Type IDN-2 as described by Hawkins is a 4/3/thin rib end such as you describe above, but with one important difference – the bottom of the top rolling is _FAT_. Based on Ed’s work, a 4/3/thin rib with a full top rolling pin doesn’t exist for cars of 10’ IH. If they do, Ed either wasn’t aware of them (doubtful), or considered them outside the scope of his work.
To the best of my knowledge, no model manufacturer has marketed a correct 10’ IDN-2 as defined by ED. Too bad, as almost 20,000 10’ cars were built with the IDN-2 end – seems like a great opportunity for a niche model manufacturer.