The sub-forum to which you refer was in the wrong place... it was intended to be a sub-forum to the 'Ford N's 9N/2N/8N' sub-forum... and was moved. As to the Eaton post in it... I'm not sure what happened to it (I didn't move the sub-forum).
The sub-forums were not necessarily intended as an "easy way for members to stick threads"... as much as it was a place to store all the sticky threads for a specific forum.
The sub-forum where the Eaton transmission thread was placed was inadvertantly attached to the Ford Lawn&Garden Tractor forum, rather than the N's forum. There aren't that many (any?) stickies in the Ford LT/GT forum... to require a 'stickies sub'... whereas in the Ford N's forum... there are several stickies.
Somehow the thread got misplaced when the sub-forum got moved.