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)

 

all it says is axle tr spr it didnt help that i had to ****

 

tell us what it says on the axle tag then tell us what it says on the door jamb. Where did you get the letters from?

 

you could also go onto some grass or ice, being your in MI, and hit the gas while going straight. If both tires spin, get the additive or use a quality synthetic that doesn't require it.

 

That actually does help. 8" of snow overnight. I was whippin her sideways and throwing snow with both back tires so..... additive it is.