Pull the
trans, pull the flywheel, pop the seal out.
The "proper" way is with a small slide hammer with a sheet metal screw in the end.
My way for 10 years at the Ford Dealer was a small screwdriver on the OUTSIDE of the seal (block surface area NOT THE CRANK SHAFT inner part of the seal). I tap the screwdriver in and pry the seal out.
It is best to have the proper tool to reinstall it if you don't have the experience putting it in the dirty way.
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2006 Legend Lime GT: Samco, Metco, LPW, Brembo 6 pot brakes with floating rotors, Magnacharger with 8-Rib, LubeLocker, Royal Purple, FR500S front end, APR Performance Carbon Fiber Rear Wing, Roll bar, 10 qt upgraded oil system...Thank you Capaldi Racing for all your help!
2007 Mustang GT/CS : Wife's Car, Magnacharged too.
1966 Mustang GT-K Code Coupe: Restored
Removing Main Rear Seal, 1987 2.3 motor 
