Yes, it is confusing to a degree (and there are at least two types of A/T shifter setups out there as well). I like to think about that there is about 1" of adjustment range in the stock linkage. At stock height, it is somewhere within that 1" range, might be dead center, but might be at one end or the other. So if it were on the upper end of the limit, the brackets might be too tall and push you over the top of the adjusability limit. Likewise if you were at the bottom end of the limit, the brackets may end up too short.

So the key is to figure out "what" is causing it to pop out of gear, as it does sound like in your case it is the body/floor moving relative to the transmission/t-case/frame that is doing it. If you can pull up enough of the console so that you can see what is going on, that may help. With a manual tranny, just removing the rubber boots is enough to see if there is any floor/shifter contact and if so, how to eliminate it.