Rack issues

Hello everyone I'm working on a customers 1983 5.0 with power steering and the original rack developed a leak and I replaced it with an aftermarket Fenco brand rack. The gentleman drove the car for about a month and with less than 500 miles on the rack the spool valve locked up, and therefore I put another rack under it, but now the second rack started leaking almost immediately, and so I put another rack under warranty. The third rack has is now leaking in the same spot as the second within a few days of use, and it leaks from where the shaft housing bolts to the rack, and when the wheels are turned the housing flexes at least an 1/8". Has anyone had this same problem and what was the solution. By the way I've put two pumps on the car as once the rack messes up it gets metal shavings in the fluid so I flush each time I put a pump and rack on.