Truck Repair: power steering pump leak, bendix air compressors, power steering pump

Question
  I have an L10-310hp Cummins in an 8100 International tractor,1992. I have an oil leak around the power steering pump,But I'm not sure if it's coming from there or the accessory drive.My question: is there a seal where the pump attaches to the block,or just the gasket? It looks to me like there has to be oil in the space where the shaft goes in,as there is a ball bearing in there. If so,the gasket has to hold the oil in,right? If it's not coming from there,then it must be coming from where the air compressor mounts to the accessory drive,I assume. Thanks for any advice,Tom

Answer
More than likely being an International,its the air compressor mounting gasket.Just run your hand under the compressor & accy drive.Those compressor gaskets leak regularly with the Bendix air compressors.If the plate has 3 bolts,it has an o ring.If it has 4 bolts,it has a gasket.