In Ford X series (other series also?) an LSD is supposed to have a red oil filler plug.
I have seen this disproved plenty of times though, and I've seen filler plugs that are rusty with no paint at all.
I have an 4.1 XF GL auto with 4 wheel discs and the diff looks a little larger than a standard diff.
I cant see or feel any LSD function present (put the car on wet grass, tromp it, and 1 wheel will spin) also no detectable drag between axles when both wheels are raised on the jack.
So I either have a very st**ffed LSD, or a plain slippery.

I did a search for diff tag numbers and other diff ID so I could find out for certain, but no results.
Any one help

If you have an LSD the other wheel on the opposite side should rotate in the opposite direction when its turned on jacks and off the ground.
If its an open centre diff they should spin in the same direction.

Geez I hope I got that right?

Anyone?

nah i think its the other way around, took a diff out of a torana last night, on jacks they spun oppisite directions and i no its a single...

ouch, so wrong!

Hand brake off.

LSD: Both wheels will travel at the same speed and the same direction WITH the tailshaft.

Single pegger: Wheels will spin opposite with each other.

However, with No load, a Non lsd May still spin the same way. To rectify this, place the car in gear or Park (with engine off) and rotate by hand.

An LSD even half shagged will be hard to turn.
A Standard will spin the other wheel backwards.

Always be cautious... safety first, secure the car with blocks or stands.

I think the LSD in my ED is gone, is it possible a fluid change will help it?

Man I got it backwards. My brain hurts.

na fluid wont help you need to shave the cones or buy new ones and shim it up, takes a while