Kevin, requiring left rudder trim for Skymasters is normal. As a matter of fact, the factory service manual calls for them to be rigged with left rudder.
I had the rigging squared up on mine and it was inexpensive to have the rudder rigging jig made up.
Details here:
http://www.337skymaster.com/messages...ead.php?t=1680
It's a pretty simple job for a competent A&P with access to the 337 Service Manual.