Re: Broken Bronco
Considering your well-described chain of events, your power steering pump may have joined the dearly departed. However, its worth giving it a test. If you take off the drive belt, put some fluid in (Type F trans fluid, NOT the same stuff as your trans uses (Mercon/Dexron2e). Then try spinning pump by hand (clockwise, I think, but look at your belt routing, crankshaft always turns clockwise to drive the belt). While spinning by hand, it will turn a bit harder once or twice (maybe more?) through the revolution, and you will hear a sound like a pump doing something inside. If its pretty hard to turn all the way around, the shaft bearing has probably died (it was lubed from the inside via the fluid) or the slippers have croaked.
Its easy to change, you will have to take the bracket that holds the pump off, and take that assembly to a parts store to have them use a puller to take the pulley off. The rebuilt pump will come with a simple bolt-type pusher to put the pulley back on. You can use your old belt in a vise, or a friend with tough hands, to hold the pulley while you work the pusher. You need a new belt. Pumps are about $50, I think.
By far the best rebuilt I have found is "ATSCO", an Arizona rebuilder, sold through AutoZones in my area (I once had to replace a pump twice more due to rebuilder problems on another brand - @#*#@&!).
I've never seen a PS pump on a big Ford die big time before. I have replaced many, usually at 90,000 miles or so, always due to a shaft seal leak. The only time I have seen fluid burp out of the reservoir (sp?) is if the steering wheel was turned hard when engine was off.
If you old pump passes the hand-turn test, may be worthwhile to disconnect the pump output, aim into can, pour fluid through a funnel & hose into reservoir while someone starts engine (watch yer hand on that fan, Sir!). See if the pump pumps good. Shut it off before it runs dry. I guess I'm saying this last part because I wonder a bit if something in your steering gear box may have closed up. But you can hook up the pressure side again, and put the return from the gearbox into a can, and look at output there too. Its worthwhile giving that pump a good visual, maybe you will find something there.
On another tangent, IF your alternator DID seize up, and the belt slipped on the crankshaft end, you wouldn't have any drive to the PS pump, and with you at the wheel turning it harder, it may have exited via the reservoir. Hey, Dad may be right! Try turning the Alternator pulley when you have the belt off.
Let us know! UncleDon
PS - If you change pump, you will need to burp the air out of the system. Fill with fluid, run, check level, fill, etc. then lift both front wheels off the ground, and while running engine, turning steering wheel lock-to-lock back and forth a few times. If you can't do this, it will make some noise due to some air still trapped, but it will get out eventually.