Allison 5sp: Gear box or P/S pump?

[J_Stone06]

So a couple weeks ago I started noticing a grinding howl coming from the steering. It started just when I turned left and now it's across the entire spectrum. I checked the fluid as a first check and everything was good as a flush was done within 6 months...I haven't really noticed a difference in performance so to speak, it just sounds god awful, especially after the truck has warmed up. Any ideas welcomed. Thanks

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[Ne-max]

Power steering pump.

 

[J_Stone06]

Power steering pump.

How would I know if it were the steering box instead? I've tried listening to the area to narrow it down but I can only come up with these two parts. If I replace the pump, is there one you would recommend? I know XDP has one, not sure if it's all that great or not. Also, would you recommend I change out hydroboost to a LML one? I'm looking for a more solid pedal with less fade. I have the typical leaky p/s lines, which have to be replaced. Thanks for the input.

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