great - I just picked up my new 05 3500 with 6spd last week. Put a thousand miles on it over 3 days with no problems except for one weird incident. Was starting off and as I engaged clutch starting hearing this major clunking noise - like something was loose and dragging. Once up to speed again never heard it again - thinking maybe I inadvertently dropped into 4th to start than 2nd.

My truck was built 8/04 - how can I determine which gearbox I have?