Honestly, it's funny you bring it up. If you're talking about the traction loss in one of the rear tires when you accelerate it's easily fixed with a new LIMITED-SLIP DIFFERENTIAL rather than the stock differential which is open.
I'm a bit upset about that one, because it would make sense to have the two rear wheels spinning together. Personally, I drive with the TCS off because I really don't need assistance when driving... but it's a pain when it's raining. The car fishtails so easily when turning I think because the wheel that gets all the traction is the one outside of the turn which brings the rear out of the APEX. Let me know if you find out anything, I will be in touch. By the way, LIMITED-SLIP DIFFERENTIALS are around $200 (+ -) USD. I will do a little research and I will keep you posted and let you know exactly where to find it. ALSO, IS THERE ANY MUSTANG THAT HAS A FIXED OR LIMITED-SLIP DIFFERENTIAL FROM STOCK?
~Garcia~
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"Drive what you build, build what you love, love what you drive." -A. Garcia
You could say: "I SPENT OVER 3K ON MY MUSTANG"
but it will never mean: "I WORKED DAY AND NIGHT TO MAKE IT RUN AND ROAR THE WAY IT DOES NOW." -A. Garcia
When you said "most GT's", how sure are you friend?... and only GT's???
~Garcia~
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"Drive what you build, build what you love, love what you drive." -A. Garcia
You could say: "I SPENT OVER 3K ON MY MUSTANG"
but it will never mean: "I WORKED DAY AND NIGHT TO MAKE IT RUN AND ROAR THE WAY IT DOES NOW." -A. Garcia
I'm fairly certain all factory built Mustangs, excluding Cobras and GT500s, come stock with open diffs. You can get a cheap LSD for around $300 new.
You'll have to do more research in order to figure out what you need, and you'll need a shop to install it for you. If you do it and it's not PERFECT it will end in disaster.
from what i know, most factory v8 mustangs come with fords version of posi which they call trac-lok
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1988 Ford Mustang LX 5.0 5 Speed
BBK Ram Air Intake,Original Flowmaster 40s dumped before the axle, Ford Racing plug wires, KYB shocks, Steeda Strut Bar
Flowtech Shorties, Steeda 34# Injectors, Aluminum Driveshaft, 70mm Edelbrock Throttle Body, Underdrive Pulleys, Ford Racing Sparkplug Wires, Smog pump Delete, Mild Lunatic Cam, Custom H-Pipe, Adjustable Camber/Caster plates, Short Throw Shifter, Metco Inc. Rear Lower and Upper Control Arm
I have a 93 lx v8 and when I got it I would get one wheel sometimes and assumed it was a open diff
then I changed the fluid and put some of that friction modifier in and whobam! posi lol
so maybe your fluid is just overdue if it is a trac loc axle...
And like I told you, most of them are around $200 USD (+ -) but don't ignore what P4452 said. No transmission job should be done at home, leave it to the professionals. They should have enough experience to install it with their eyes closed, and they still chose not to do it. It's a very complicated thing, not recommended for us mechanics with average or little experience. So, let them do it unless you wanna have the two rear wheels "WONDERING" down the highway apart from the car.
I'm hoping to get one too, that one wheel wonder is a bummer. But first I need a job.
~Garcia~
__________________
"Drive what you build, build what you love, love what you drive." -A. Garcia
You could say: "I SPENT OVER 3K ON MY MUSTANG"
but it will never mean: "I WORKED DAY AND NIGHT TO MAKE IT RUN AND ROAR THE WAY IT DOES NOW." -A. Garcia
All fox body 5.0 were all equipped with t-loc.....
yea, from like 83gt up with v8s and even some of the older 4cly. performance editions. I think is how it went I know in 85 the v8 Stangs all had LSD till present day.
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Just another 10sec. street Stang. Turbo baby.. just outside the 9s.... Still only 306 CID....
i use the guts from a 96-99 explorer 5.0 8.8 they have 3.L73 gears, 31 spline axles and t-lock
you can get a t lock case from most ford trucks and suv's then go on you tube and rebuild it ure self, i would go ahead and upgrade to 31 spline axles while you have it broken down
it cost me 350.00 for a 31 spline case w/ the extra clutches at a local diff shop 2 days before a race
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1990 GT 5.0 T5 3.73 4 wheel disc brakes, ported gt40 heads w/ tfs spring kit, tfs street intake E-CAM +4 advance, bbk headers,cold air and h pipe. spec-1 clutch w/ promotion adj cable and firewall adjuster.i took a 5.0 from a 96 explorer w/ 97k, i swaped the intake and cam ported the heads......WOW this thing now rocks for only a few hundred dollars to do the entire swap, well worth. i am currently chasing a idle surge issue
How to stop one wheel wonder 
OPEN REAR WHEEL TRACTION in MUSTANGs 
When you said "most GT's", how sure are you friend?... and only GT's???
