Power steering pump 85 high sierra 2500

[treetop_73]

I just bought my 85 and noticed there was a slow leak from the gearbox but just checked the power steering fluid level and it is dry. There is a stain on the street under my truck that is dry but I don't remember it being there before I bought the truck. Its been parked for about 3 weeks since I bought it as I haven't got insurance yet. What typically causes leaks and do you think the pump needs replaced or refilled or what else?

I've always wanted an 73-87 and finally got the wife to agree and now this minor roadblock.