I have a 2007 F150 FX2 with an axle code of B6. From what I can find out it is a 3.73 limited slip. My question is what size ring gear? Is it a 9.75 or ? How many quarts to drain & refill? Thinking of using Lucas 75w140 synthetic with Ford XL-3 additive. Your thoughts & suggestions? Thanks.

 

 

 

I used the Lucas Synthetic Limited Slip 75w140....It is fine, just a little more $ than a 'standard' oil. It's been in there for about 30k with no issues. Just make sure to still add 4oz of the MC XL-3 even though it says it's already for LS rear ends. This came directly from a Lucas rep.

 

Ended up going with Valvoline synthetic instead of Lucas. Buddy quoted me the wrong price on Lucas. Use Valvoline in just about everything & have had good luck with it. And I won't forget the MC XL-3. Thanks fella's!

 

The axle code doesn't tell you which axle you have, just how it's configured. The axle choice is determined by powertrain and/or payload packages. I think FX2 gets the 9.75 but not sure. It's easy to tell visually though, the 8.8 has a cover that's basically square with radiused corners. The 9.75 cover is a trapezoid with radiused corners and looks just like a Dana 60 cover.