1. Use the Fill Bolt: Some Ford 9-inch differentials may have a fill bolt located on the bottom of the housing. If your differential has a fill bolt, you can use a gear oil pump or funnel to add fluid through this hole.
2. Remove the Rear Cover: If your differential does not have a fill bolt, you can add fluid by removing the differential's rear cover. You've used a gasket scraper or pry bar to remove the cover and add oil until it reaches the bottom edge of the fill hole. Replace the cover with a new gasket.
3. Use a Fluid Evacuator: If your differential has no oil plug or fill bolt, you can use a fluid evacuator or extractor. Insert the evacuator tube into the differential housing until it touches the bottom, and then start a siphon action to draw in fluid.
