Use a new T/A rear end cover, 31 spline axles, and upgrade the lower control arms. By the way what part of Jax are you from? I'm from Atlantic Beach off of Mayport RD but here at Fort Bragg, NC.
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97 Mustang GTS Laser Red 5spd, MSD coil packs, Cross Drilled and Slotted Rotors,Ford Racing 9 mm wires, Ported and polished upper intake Plentium, 70 mm Accufab TB, Steeda intake spacer,
March underdrive pulleys,3.55 FMS Gears,C&L 80mm MAF,C&L Power pipe, Sub-frame connectors, Mach 1 tokcio shocks and struts, Mach 1 chrome rims with 255/45 17 tires, 125 HP NOS dry nitrous kit,B&M Ripper shifter,Maximum Motorsports lower control arms, 2 chamber flowmaster 2.5 in,BBK offroad X-pipe, 218.3 RWHP 49
I have seen guys run 13 second cars and break stock axels and guys running 11 second cars with no problems. If you are running drag radials, you should be fine, slicks, I would redo the rear. I'm looking into this now also, and plan on a downs rear end cover, auburn differential, 31 moser spline, with 3.73's. Your looking at 600-700 dollars in part with no install...but hello slicks!!
Good luck,
Jules
The T/A rear cover is a brand. MAC, Steeda etc.. carry them also it is stronger than the stamped piece from ford and puts extra support on the cap bolts.
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97 Mustang GTS Laser Red 5spd, MSD coil packs, Cross Drilled and Slotted Rotors,Ford Racing 9 mm wires, Ported and polished upper intake Plentium, 70 mm Accufab TB, Steeda intake spacer,
March underdrive pulleys,3.55 FMS Gears,C&L 80mm MAF,C&L Power pipe, Sub-frame connectors, Mach 1 tokcio shocks and struts, Mach 1 chrome rims with 255/45 17 tires, 125 HP NOS dry nitrous kit,B&M Ripper shifter,Maximum Motorsports lower control arms, 2 chamber flowmaster 2.5 in,BBK offroad X-pipe, 218.3 RWHP 49
my buddyss 98 cobra with 410 gear running 12.9s with a few bolt on's snapped his axle, had to call a toe truck at the track...ouch..he had his best 60' foot time on the previous run if that counts for anything..lol
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BBK H-pipe
2 Chamber Flow's
Ford Motorsport Wires
K&N
Timing Bumped to 12*
Best time= 14.7@93 MPH
136,000 Mile
Rear End Upgrade 
