As the former owner/operator of a driveline shop I think I can offer solid advice on this subject. I have literally made hundreds if not thousands of drivelines of all descriptions from the smallest of small to the largest used on drilling rigs. It is a simple matter but not for the inexperienced or under=equipped. It requires a lathe and dial indicator plus misc. small grinders, etc. not to mention skill and patience.
If you do not have these tools and the knowledge to use them then by all means take it to a driveline shop and have it done. Shortening a shaft is simple and inexpensive. It can be done while you wait if they are not busy. Done properly driveshafts do not need to be balanced. That is a production method shortcut to speed up manufacture.
Don't be misled by unknowledgeable people who don't know what they are talking about.
