Here is my disclaimer: I am a noob. I just recently took my truck apart for the first time. I am an engineer by trade so this stuff is very second nature.

1. Refer to step 62 in your manual. Look at part GS043. In the next step (step 63) they show a 5 * 5 set screw that secures GS043 to the output shaft of the front differential. This is the first thing I would check. This setscrew should have thread locker on it. There is an access hole drilled on the bottom plate between the 2 posts that secure to servo saver and center link to the truck. I *think* you should be able to see and access this set screw thru that hole. If not you may have to pull the front of the truck off. Its very easy to do, just follow the steps in your manual.

2. There are 2 pin (GS009) assemblies that secure the drive shaft itself to the transmission and GS043. Refer to step 62 to view the front pin and step 30 to see the pin for the transmission. Both these pin assemblies use 2 "E" clips to hold the pins in place. Make sure all "E" clips are present.

3. You may have snapped the GS009 pin assemblies. Unlikely, I think, but it is a possibility.

I still have my truck completely apart so if you want any pictures of any subassemblies let me know.

Check that stuff and let us know what you find...

Joe