I have an 84 lincoln rear end(8.8, rear disc)...but a wheel with 4.5" backspacing sticks out 1/4" past the top of the fender, I'll simply use late model wheels to bring this back in so for me its not an issue...as for a fox 8.8, i believe they are too wide(don't quote me on that though, I never attempted it so I haven't done any real research on it)
Yes I have.
The drive shaft from the fox would need to be lengthened. IIRC the Fox is about 46", and depending on transmission/pinion yoke, the Mustang will be about 50". So you take it to a shop with the measurements, and they weld in a new tube. Cheap and easy.
There is a write up on one of the 8.8" installs I've done on the website in the signature below.
Pretty easy, and has been done so many times, that there is enough information to fill up a Wiki site.
Do some searching, and you'll find some really cool installs from different guys here, and on other Mustang web forums. There are also other 8.8" options you should look at as well, like the Explorer swap.
It's a better option for the 31 spline trac-lok, and 3" axle tubes. The Fox has 28 spline Trac-lok and 2-7/8" axle tubes. So the Explorer *should* be able to handle even more power.
Now the next part seems very hotly debated. So I will only offer my personal opinion (and we all know what *opinions* are worth ).
ABS and track cars work well with 4 wheel discs. Street/strip cars work great with rear drums.
So if I'm putting discs on the back, by default I also want the least amount of unsprung weight as I can get. That eliminates the Explorer rear end completely. Everything about this rear is heavy.
That's why I like the Fox with Cobra discs, 31 spline axles, and a Tru-trac. It's wicked light, and takes some serious abuse.
Again, just my personal opinion.
I just finished up installing a 2003 8.8 in my 66. The tires stick out about 1.25" per side but I'm using deep backspacing wheels. 66runt has some very good information. I agree on the driveshaft length for the fox. I am at this stage with my project. I'm going t use my existing driveshaft and a mate a fox driveshaft-flange.