2000 Explorer 3-4 slips OD light flashing . What is the fix .

Check for codes.

This happens all the time if Explorers the existing unit will need to be replaced with a updated remanufactured transmission, you can get on for $1399 from Remanufactured Transmission & Engines US : home (http://www.main.nationwidereman.com)

If you need a rebuild, check out Fred Jones Enterprises, LLC, which is a Ford Authorized Distributor of Motorcraft and Ford Remanufactured powertrain assemblies:

Fred-Jones.com (http://www.fred-jones.com/catalog/connector/)