To find the specifics of the drivetrain coverage, you'd need to:
* Locate the original warranty paperwork: This is the most reliable source. It will detail the length of coverage (likely in years or miles, whichever comes first) and what components are included under the drivetrain.
* Check the owner's manual: While it may not contain precise warranty terms, it might have a summary of the warranties included when the vehicle was new.
Without access to these documents, it's impossible to give a definitive answer to the length of the original drivetrain warranty for a 2006 Ford Explorer. It's highly likely that the original warranty has long since expired.