Do you need to add it in a V6 when changing the differential fluid? Im planning on going with PR or M1 Syn fluid. I think I read somewhere the V6's do not have a lsd therefore does not need the modifer, is that right or wrong?

Thanks,

 

I suspect you're correct (that not having LSD means you don't need the modifier) but I'd wait until you hear from a V6 owner that has replaced their diff fluid... successfully.

 

You are correct.
LSDs only need friction modifer

 

I'm swapping the 7.5 for the 8.8 this weekend and need some friction modifier along with the diff fluid. Any suggestions?

Probably gonna go with 2 bottles of this:
http://www.americanmuscle.com/royalp...0-gearoil.html

Edit: wrong link

 

Thats what I plan to use but in the 75-140 weight. Thanks for the info on the friction modifier.

 

Are you using the heavier weight because your going with a bigger gear?

 

That's what I put in my 8.8/3.73
And although RP says you don't need the FM,
I bought the little bottle of FM from Ford and put it in.

 

Someone suggested that but it seems like the 75-140 is the way to go

That's probably what I'll do.

How do you like the 8.8 & 3.73s vs. stock?

 

I like it a lot. Quicker acceleration of course, and the rpm's aren't bad on the interstate.
MPG is better in town. Worse on the highway. But not by much.
I just ordered the 4" Shaftmasters aluminum DS.
Should deliver next Monday.

 

I've used RP with the friction mod already in it - have had no probs w/o adding xtra. my .02