Screaming Power Steering Pump

[chika989]

Would much appreciate your thoughts on my situation:

1987 Chevy 3/4 ton pickup 350

I've replaced the power steering pump five times as of today.....four pumps from Advance and the latest one today from NAPA. I've replaced the gear box, new hoses, drag link, stabilizer and tie rod ends (new fluid and bleeding as per mechanic's instructions). The screaming continues!.....not continually but at start up and when the wheel is turned...there is some difficulty turning the wheel.

Don't know where to go from here. I'm no better off now than I was five power steering pumps ago and many man hours as well.

Any suggestions would be much appreciated.

Thanks so much.