Yes, there is a plug that goes into the block that if it isn't there you wont be able to obtain a good oil pressure, but I doubt thats the problem here...sounds like a freak occurance. At least you caught it before any damage was done.

 

Finally got it back together last night. Oil pressure is about 80psi - cold and 35-45psi - hot, at idle. Runs like a champ. Still not sure the order of events but the pump locked up, drive gear sheard off, and the shaft spun inside the pump gear. I think the pump probably went first. At least I know everythings new now. Thanks for your help. Nathan