I am aware of three Improved Dreadnaught Ends made by Intermountain for their 10'0" IH box cars. All three have pins on the backsides to place into IM's 10'0" box cars, including their '37 AAR car
IM tooled up their only one of the three ends with poling pockets for their NYC "Pacemaker" cars. This was a "thinless" end (3/4 IDE) Some SP cars used these ends.
IM did another "thinless" end, without poling pockets
IM made one end with a "thin" top ridge. (thin+3/4 IDE) This was the standard end for their 12-panel box car.
The pictures are in descending order
I believe those are the Intermountain ends that were designed for the '12-panel' 40' boxcar. The spotting feature are those holes across the middle rib, which were intended for use with the (after our era) crossover handrail. Intermountain has produced a bajillion RTR versions of this car. Then they discovered that the same ends were appropriate for the 10-panel 10'0" car that they conveniently already had all the other parts for. One group of these cars not mentioned below is C&O 17000-17999, which I remember because I'd bought a set of these ends and was almost ready to kitbash one when the RTR version was announced.