In this write up, it will show you how to change the rear differential fluid in your Ranger. This was performed on a 2001 Ford Ranger XLT 4x4 rear differential with limited slip. I chose to run synthetic gear oil with the limited slip addidtive Tools required: Socket set Air ratchet (optional) Sand paper (fine grit auto paper) Gasket or sealant for differential cover Eye protection Brake cleaner Gear oil Oil drain pan Step 1 Remove the fill bolt located on the rear of the differential, by inserting just the 3/8 ratchet head Step 2 Loosen the bolts holding on your differential cover, pull the cover out slightly and allow it to drain in your oil drain pan. Step 3 Remove the bolts and the differential cover and allow time for the rear to drain Step 4 While the rest of the rear diff drains, use a fine grit auto sand paper to sand the surface where you will be sealing the cover again. **In this writeup, I replaced my diff cover with a new one with a gasket, if you are putting the same diff cover back on, you will need to sand the surface of that cover as well to ensure you have removed the old gasket/sealant. Also allow ample time for it to drain well. Step 5 Clean the rear using brake cleaner. **If you are using the same diff cover, clean it in the same manner. After the rear was cleaned with brake cleaner, you may wipe it down or blow it out with a compressor as I did. Please wear eye protection in this process!! Step 6 Replace the rear diff cover, using a gasket or a liquid gasket/sealant. **Liquid gasket or sealants must be applied to the cover itself and should be applied around center to inner edge under the bolt holes** By hand, insert the bolts that will hold on your diff cover, then tighten with a ratchet. Step 7 Fill the rear diff with your new differential oil. **Check your owners manual for appropriate amount that it needs. Trucks with limited slip rears MUST use a gear oil with the limited slip additive in it** Step 8 Once the rear diff has reached capacity, replace the fill plug, turn it in by hand first, then using the 3/8 ratchet head tighten the fill plug.