Rear differential

I have been researching this problem and spoke with numerous techs on the phone and still to no avail. I have not solved the problem. About 5 years ago I began assembling parts for the rebuild of my 69 Dart GTS and some of the parts were the green gearings for the axle shafts for the 8 3/4 Posi differential I also sent out the differential to be rebuilt, fast forward till now, I have all of the components installed and ready to test the rear end, I have the rear of the car on stands to test the speedo which works fine, however, when the car is in gear the rear end made a huge racket and sounded like the bearings were square. Ok so here is what I found the axles are not going into the carrier far enough, they only go into the differential spline about a 1/8 inch, I measured the total length of the axle and came to about 27 inches or so up to spec, I went ahead and checked to see if the green bearing were seated all the way down, they were. Nothing has changed on the rear end, with the exception of the green bearings.

This sounds crazy I know I have had the diff out 3-4 times I am looking into tearing into it to see if there is anything that stares out at me, the shop that rebuilt the diff said it looked fine and changed all of the bearings and cones. I did remove the axle seal in the tube on both sides, any help is appreciated.