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No the trans does not require an external pump. Jeff has added a pump to the trans. So now he has two hydraulic pumps. One each to supply the hydraulic fan circuit and another to supply the steering gear box. In later model years Newell  began to use a setup like this for all the reasons that Jeff has elucidated.

I know where I went wrong, he said ZF gearbox and I assumed transmission, he is talking about the steering gearbox. 

Thanks for the summary Richard, if I would have read the entire thread I would have known he has an Allison transmission. 

So this is good to know, I think I may be having a similar issue with mine. I have been getting some whining noise from my pump and occasionally my steering goes "dead", no power assist. I attributed the issue to the fact that my hydraulic filter looked like it had never been changed, appeared to be an original vickers brand filter that was in bad shape. First thing I did was change the filter, but no change in the whining or the dead power steering issue. I did however gain a leak at the pump now. Some of this was from when I loosened the line. I tightened the line some more and it reduced the leak on this last trip to Tennessee but I still have a leak. I went ahead and ordered a brand new pump and I need to get that installed. I will see how things are after I replace the pump. 

I may look into a way to add another pump if the issue persists. If I go that route I may see if I have room to run a 2 section pump instead of trying to add a second pump. Wanderlodge went this route with their coaches as well, the two section pump is effectively 2 pumps in one. Not sure if the gear on the engine can handle this load though, I will have to verify the specs on what can be driven on the engine gear. 

Is there a reason why you went with second the pump on the transmission instead of a 2 stage pump?