The motor itself will likely fit with significant modifications to the chassis, however it will not be a direct swap. This will be costly and will require the entire swap of the ECMs and all other electronics to go with it.
For a 2001 Ford Explorer Sport Trac : There are ( 6 spark plugs ) for your 4.0 liter V6 engine
The only factory engine in a 2004 Ford Explorer Sport Trac is the 4.0 liter Single Over Head Cam , V6 engine which has ( 6 engine cylinders )
The Ford 4.0 liter EFI , V6 engine is an Over Head Valve / pushrod design engine ( the 8th " character " of the VIN is an " X " ) The Single Over Head Cam engine is VIN " E " on your 1999 Ford Explorer Sport
For a 1999 Ford Explorer Sport : Both the 4.0 liter EFI , V6 engine and the 4.0 liter SOHC , V6 engine take : With engine oil filter change : ( 5.0 U.S. quarts of 5W-30 )
The 4.0 liter SOHC , V6 engine in a 2001 Ford Explorer Sport Trac takes : With engine oil filter change : ( 5 quarts / 4.7 liters of engine oil )
With engine oil filter change ( 4.7 liters of engine oil ) for the 4.0 liter SOHC , V6 engine in a 2002 Ford Explorer Sport Trac
The 4.0 liter OHV engine is rated at ( 160 horsepower ) The 4.0 liter SOHC engine is rated at ( 205 horsepower )
210 horsepower for your 4.0 liter SOHC V6 engine
With engine oil filter change : The 4.0 liter V6 engine in a Ford Explorer Sport Trac takes ( 5.0 U.S. quarts of 5W-30 )
A 2001 Ford Explorer Sport , with the 4.0 liter Single Over Head Cam V6 engine should have ( 4 oxygen sensors )
On a Ford Explorer Sport Trac : 4.0 liter SOHC , V6 engine ( 6 fuel injectors ) 4.6 liter V8 ( 8 )
Yes , the 4.0 liter SOHC V6 engine in a 2002 Ford Explorer Sport uses the Motorcraft FL-820S engine oil filter according to the Owner Guide