graybeard
the DC9 has a hydraulic ram to ensure nose down elevator because the elevators are aerodynamically powered ...not hydraulic, and there might be some scenarios where air flow would be insufficient.
IT IS NOT A stick pusher. If th pilot wants to activate this ram, you must manually push the yoke full forward...indeed the copilot checks it prior to each takeoff...you may notice if taxiing behind an MD80 or DC9 that the elevators are frequently flip flopped...one up, one down...hit the yoke forward and the ram puts them both down.
AS to strakes...yes on the later models...they replaced the vortilions on the earlier DC9's...these little things on the wing sort of looked like a tiny drop tank, but improved air flow to help avoid stall problems. I don't think the MD80 has a pusher.
I think the BAC111 and the Trident are examples of two T tail jets with stick pushers.
PJ2...the DC9 30 most certainly has vortillions...they look like little fuel drop tanks on the front part of each wing.