I realize it may be "best" to have drive shaft work done by a pro.
With that being said, alternatively I have seen 2 suggestions online. One is by cutting the u-joint "cap" off one end of a shaft itself, cutting the tube shorter, then re-welding the cap back on. Another shows cutting a section out the actual tube then re-weld using some "C" channel as guides to align them back.
Both versions one would need to scribe alignment marks to keep both ends aligned. Also seen a suggestion for adding ATF fluid inside the shaft tube... helps with balancing.
Anyone care to add comments, suggestions, pro/con, or experiences?