If the boot is bad, the ball joint is shot... you can't just replace the boot anyway (to my knowledge). The uppers only come as a unit, you cannot replace just the ball joint it is NOT available anywhere... The newest of our cars out there is 7 years.. the ball joints, and most of the front and rear suspension bushings, bearings, joints, etc. are all due or over due on any one that hasn't yet replaced them, unless you have unusually low mileage, and even then, I had to replace uppers in the '95 with under 40k.... Florida weather is hard on rubber and plastic parts.
A word to the wise... if the uppers are bad, check the lowers, too.. and it would be smart to look at your front and rear sway bar end links, strut arm bushings, knuckle bushings, shock mounts, etc, etc, etc.... Yup all of it.. it's pay me now, or pay me later. If your lower ball joints need replacement (and the probably do), my advise is to replace the whole arm and get the new bushings as well, although you can just get the MOOG ball joints, but have to have the pressed in (they have the zerc fittings though, the ones already in the new arms don't)...
The good news is that there are poly MOOG poly replacements for almost all those parts available at Rockauto.com at good price which are superior to OEM... or Richie at MN12performance.com has poly replacement sets of bushings..
'96 T-Bird LX 4.6L Alive & well & living in S. Florida
N/A: Renegade NPI heads/Comp Cams; OEM intake manifold; Bolt-ons
245 rwhp; 13.713 @ 99.35 (Commerce, GA - November 2003)
BLOWN: Renegade NPI heads; Renegade shortblock; Intercooled T-Trim; some other stuff
Pump Gas Numbers - 547 rwhp / 525 ft.lbs; Best Time - 11.388 @ 118.68 (Commerce, GA - November 2007)