I have a 2001 ford ranger xlt with an auto trans and 4.0 i know it has an 8.8" rear end with 4.10 gears but dont know if its open dif or limited slip because im getting ready to change the fluid in the rear and front and dont know if i need the limited slip additive when i do it. Thanks.
Post the axle code off the drivers side door sticker.
also you can check the axle tag. It should be a metal tag on one of the diff bolts
it will say something like "8.8 4L10" (limited slip) or "8.8 4 10" (open)