Does anyone know how many suits of power armor I can leave at red rocket truck stop before I should worry that they will spawn away. Note that none have fusion cores in them as I took them out when I store them there. I'm looking at 9 suits of power armor there now
Power armor in settlements will never disappear. You can have as many suits of power armor as you like in a settlement; there is no limit, even without fusion cores.
Please note that this only applies to settlements. If you leave power armor in the wilderness, it will despawn after a given time.