Upgrade CiviCRM 3.3.2 to the latest on Drupal 6
From CiviCRM 3.3.2 to 5.x latest is a huge task. Lots of things that can go wrong in the process. And if anyone has ever made any schema edits to your CiviCRM database tables upgrading could be very painful.

Have you considered installing a fresh 5.x and then doing an export out of 3.3.2 -> import into 5.x of the data you want to carry forward?

It will be much easier if you treat this like the same as any migration from a legacy CRM to CiviCRM 5.x; 

CiviCRM 3.3.2 was released on Jan 04 2011 - it qualifies as legacy :-)