Right, well, I picked up the new part down here locally and they only had one left and weren't positive it was the right one. It wasn't. Good news is one of the guys down there agreed to replace my power steering rack for me in a few weeks so I'm glad I went there anyway.
Got home and took the old one off with many a dropped wrench and quite oily hands. New one wouldn't fit, so I put the old one back on and tightened it a bit. I happened to notice that it wasn't very tight to begin with, but I figured I might as well install the new one anyway. This seems to have solved the problem; no more warning light after a 30 minute drive or a 15 minute idle session. Gauge pressure didn't change much at all. I'll have a look-see in the morning to see whether any of the oil spilled out, but my dad and I checked it after 15 minutes of idling and none was leaking out.
Thanks for your help guys! I've decided I'm going to get this thing running like a top with some money I've made from work (my original savings for a new car

). My mom's not too happy about it, but she'll get over it.
I'm sure I'll be back soon!
