Allow me to elaborate,
As Joe already mentioned there is a dampener in the middle of the Motorcraft OEM rear Toe Adjust Linkages.
see pic,
See the black OEM linkages? See the bulged portion near the end, right after the jam nut ?
Compared to the RimmerBro UK Jaguar aftermarket, the silver non-painted linkages? It has none, just a straight shaft.
On the OEM's that portion is a dampener, spring loaded I suppose, it's called "Rear Passive Steer".
It allowed for the rear toe adjust to flex a bit during turns, basically the rear wheels are allowed to follow the car around turns.
It's ever so small, you'll never notice it, I bet it's less then a half an inch if that.
On the Deeza's or the RimmerBro UK Jaguar aftermarket rear toe adjust linkages, there is no dampener and thus is a solid rear toe alignment.
Some prefer with rear Passive Steer, some don't care for it and some like myself, just think it's not enough race car and they are cheaper.
Works all the same ... if anything it makes the rear end feel more tight and kicks it straight around the turns.
So far, I've put the Black Deeza's when they were available on my silver 01 LS V8,
Motorcraft OEM on my wife's black 03 LS V8 and the RimmerBro UK Jaguar aftermarket linkages on my black 04 LSE V8.
I enjoy my 01 V8 the most, it's like a little go-kart, it's so tight ... mind ya, I pretty near rebuild the entire underneath of that LS, all linkages, couple control arms, Sport shocks and lowered it on Eibach springs.
If your boots on the end are busted open and all fouled up, you'll have excessive play in the rear end toe adjustment and this will give the rear end of the car a swaying and wobbling feeling, not true to it's center. You need to replace those along with your rear sway bar end links and get it aligned by a shop. Usually you would make sure the front end is up to par and go for a four wheel alignment.
Hope that helps!
GLWR