2nd Gen Non-Engine/Transmission 5th carrier bearing just replaced

[Cummins-Curt]

My 01 3/4 ton 4x4 auto with 126,000 can't keep carrier bearings in place. I've gone through 5 and just came from the shop today with #6. Under load pulling trailers they are knocked forward out of the mount. This time the independent driveline shop is involved and got measurement empty and loadedwith 1000# in my dump trailer. The back shaft moved foreward about 1/2 in. and the front shaft moved foreward about 3/8 in. This is a light load and not under torque. Anybody else having this problem? Any suggestions would be appreciated. Thanks