Royal T, Mine seem to have a shroud around them that prevents a socket getting on it...??
alsohow do you get a pipe on if you have a socket on it to open and close it. ?
1/4" drive - 5/16" 6 point deep socket will work. If it has been a while since they have been moved soak them with penetrating oil (PB blaster work well).
after soaking the front nipples with the blaster, i still managed to snap off the passenger side. it broke off and its so clogged there is nothing coming out of the hole...DOH!...i used a 5/16 rear and 10mm for the front.