Working on the 2002 9.75" swap into my '97, and was wondering what brand of fluid y'all recommend. It's supposed to be a limited slip, but I've also been told it's a locker. Did Ford put lockers in factory? the rear end tag reads:

3 V 919 A
SL 55 9 75 1M13

This IS a Limited Slip, isn't it? What brand and type of fluid do people recommend here? What about friction modifier? Would I find better for less at the auto-parts stores than at a stealership?:o

Thanks all.

 

It looks to be a LS 3.55. Specs call for 75w140 synthetic and a bottle of the friction modifier.

 

FORD MOTORCRAFT 75W140 Synthetic with THEIR Friction Modifier. AutoPart store Friction modifier in the tube is JUNK.

 

Royal Purple 75-140...better and cheaper than the Ford stuff and already has the friction modifier in it.

 

How much--haven't looked through the owners manual to see. Not sure it's listed, as I don't think they ever intended for people to mess with their rear-ends--that didn't come out right, anyway, I'll check into it. I've got a higher volume rear diff cover en-route--extra 1/2 quart. Every little bit helps.

Royal Purple? Will give it a try. O'Reilly's? NAPA?

 

Both O'Reilly's and NAPA carry RP on the shelves, though it seems like O'Reilly might be cheaper. $11.99 I think. The 8.8" takes like just shy of 3 quarts I believe...not sure about the 9.75, but it'll be in the manual. I've been RP in my entire driveline for years and love it. (tranny, transfer case, diff's)

 

Both the 8.8 and the 9.75 hold 5.5 pints with a stock cover.