How do you know if your car has limited slip dif??

[1987cp]

PosiTraction was the term used by Chevrolet to denote a clutch-type limited slip differential.

[91grandmarquis]

thanks.

[porschpow]

Axle codes
Open/Lock/Ratio #
-----------------------
G / H / 2.26
B / C / 2.47
8 / M / 2.73
7 / - / 3.07
Y / Z / 3.08
4 / D / 3.42
F / R / 3.45
5 / E / 3.27
6 / W / 3.73
2 / K / 3.55
A / - / 3.63
J / - / 3.85

So if I have A JY on the sticker, it's an open diff.

Can I still use synthetic oil?

[pantera77]

Those codes only apply to boxes and IIRC early aeros.

You can run syn if you want to.

[porschpow]

Would JY be open?

So IO would be ok with synthetic 75 w 90 I think it has LS written on the mobil bottle

Is the torque spec the same as a box panther, 15 ft-lbs? for the diff cover

[jaywish]

YES either way.

Look for the "S" spring when you open it. That is"posi"tive confirmation as I think Gadget mentioned. If you have posi it may very well need new a new clutch set.

If you are changing the oil, check the outer wheel bearings. remove brake (drum?) and any needed springs or shoes. Lift the axle straight up where it comes out of the housing. There should be about no play up and down. In and out of the housing is fine. If you have up and down play, basically you need new axles, bearings and seals.

If there is a good amount of metal in the bottom of the diff housing I suggest you remove the axles as well just to clean the tubes. If the bottom of the housing is reasonably free of metal and you have no outer up and down axle play and you don't need clutches. put it back together and fill it. 1.9 Qts.

You have a choice, gasket or RTV. If you use RTV, which I like, you should put on the RTV, let it dry 1/4 or 1/2 hr? then install and torque the cover. Let dry before filling.

Good luck.