Hello volcomkrew2, yes that is your driver's side outboard CV joint. The rubber bellows boot has torn, and the grease is being flung out.
Do you have any idea how long the boot has been torn?
No matter what, this is bad. You have 2 courses of action for resolution:
-remove the CV axle assembly, disassemble the outboard CV joint, clean, relubricate it, and install a new boot
-install a new CV axle assembly and be done with it. Rockauto.com has new CV axles for 2nd generation Explorers for around $50 plus shipping.
Here is a link to the Rock Auto catalog, look under 'Drivetrain' for CV halfshaft assembly.
http://www.rockauto.com/m/mobilecatalog.php
The consequences of doing nothing are a failed CV joint. With the boot torn, grease gets out, dirt and water get in. If left long enough, the CV joint could lock up.
Good Luck!
Seth K. Pyle
