For years, I ran a stock 28 spline/Traction Lok with 3.55 gears in my daily driver/weekend dragstrip car. It was a 78 fairmont, with a warmed over 302 and T5 5 speed, which weighed 3340 pounds with me in it. Over the years, I must have put 500 1/4 mile dragstrip passes on that car, usually with 8 1/2x26-15" slicks. The car ran low 13s, letting the clutch out at 2800-3200 RPM, and I never hurt the 8.8. At least, until I decided to lean on it harder, to try and get a 12 second ET slip, which I did, by launching at 4500 RPM, (12.80 @ 106 MPH), but after a couple of such higher RPM launches, I broke a stock 28 spline axle. Installed another stock axle, and kept racing the car, albeit, at the lower 3000ish launches, and never had any further issues. That said, I imagine a 2004 Mustang is likely at least a couple hundred pounds heavier, but with drag radials, and a much lower launch RPM, I would be surprised if you had any issues, unless you have a real aggressive "Snively Whiplash" type clutch. No idea if the 2004 would have 28 or 31 spline axles, but if they are 31, I would have no concerns. I ran mid 10s in my 85 Mustang, with a 331 SBF and Jerico 4 speed, launching at over 6000 RPM, with Moser 31 spline axles, and never hurt the 31 spline axles.
