I have to think this is one of those Bolens engineers thinking, let's build this great tractor, but put this one little thing that will probably fail, and to replace just a cotter pin requires tearing half of the machine apart. One of those funny little engineer jokes that they laugh about when designing it, but never have to actually deal with it. I said to hell with that and just drilled a hole in the plate in close proximity to where the cotter pin was.
In other words, yes, I eventually found where the cotter pin goes, and yes, it was split in half. Stupid design.