2nd Gen Non-Engine/Transmission clutch problems

[CapitalDiesel]

We have a 1998 dodge 2500 that we put a South Bend Mu 13-1. 25 con ofe clutch and a heavy duty hydraulic assy. two times and now the customer say's that it is doing it again. Here is what is happining! After installiation everything is fine. but after driving the truck 500-1000 miles, the truck when comming to a stop, and in neutral, feet off pedals would creep. Also if you started truck in gear, transmission would be hard to get out of gear. seemed to get worse when hot. South Bend sent us a new set again, and we returned the warranty clutch for them to inspect. they said everything was ok. Told the mechanic to look for somethngs, we did and nothing noticeable. Samething again, and now for the third time it's doing it again. What is going on? Brian