Won't pull it self in od from a stop but once moving it works fine

[needhelp02tahoe]

Ok we'll first off I would like to say thank you for your time but down to the point I was coming home from work last week when I meet a guy I work with at the stop light so I loaded my truck up and as soon as I let off the break the most gut wrenching sound came from the rear end so yeah it was shot to about twenty pieces so I ordered a new one and I got a eaton posi limited slip diff with 400lb springs but after putting the new diff in my hoe won't pull it self from a stop in od but I can shift it to 2nd and get rolling and shift back to od and it will shift to 3rd and od on its own just wondering what this could be also I just replaced the trany in November any help is much appreciated