Diff. fluid question

[X-Firechicken]

So, I had my 3.90s installed last week and I've been smelling gear oil all week. Today I put the Stang up in the air to check it out and it looks like the filler plug wasn't tightened all the way and is leaking. What is the proper fill level and what type of fluid should I add if it's low? Any help is appreciated.

 

[COramprat]

So, I had my 3.90s installed last week and I've been smelling gear oil all week. Today I put the Stang up in the air to check it out and it looks like the filler plug wasn't tightened all the way and is leaking. What is the proper fill level and what type of fluid should I add if it's low? Any help is appreciated.

Fill it to the bottom of the fill hole. Use your pinky to check but be careful. Fat pinkies get stuck.

 

[Dark Knight GT]

75w-140 synthetic read diff. fluid from motorcraft is what the book calls for. If you can find that, Ide just use either Mobil 1 synthetic read diff. fluid or Amsoil 75w-90 synthetic.

 

[X-Firechicken]

Thanks guys!

 

[GinoGT]

2 quarts will get you up to the fill hole.