Differential question

[Navy Ford Guy]

People,
I need a favor here. My Mother lives in Tucson, Az., and wanted to know about getting some preventitive maintenance done to her car. With the miles on it, I suggested having the diff lube changed out. Her car is a 1997 Mark VIII. Does it have a limited slip rear that requires friction modifier? I know nothing about these cars.
Thanks

 

[driller]

Stock would have no limited slip and thus need no additive.

Service interval for the differential fluid is 100K.

I use use a high grade 80W-140, a synthetic blend.

 

[Navy Ford Guy]

Stock would have no limited slip and thus need no additive.

Service interval for the differential fluid is 100K.

I use use a high grade 80W-140, a synthetic blend.

thank you