Rear drive shaft seal is leaking

Are you talking about the pinion seal? If so, you'll need to remove the drive shaft from the rear and move out of your way. Remove the pinion nut, pull out the old seal, you can use either a pry bar or even a flat tip screwdriver. When installing make sure not to damage the new seal. Lightly tap on the seal with a hammer or dead blow hammer until flush, then reinstall the pinion nut and drive shaft. Don't forget to top of the 90/w oil. Hope the info helps.