Performance Upgrade. If your running a heavily modified or forced induction S197 Mustang, your factory axles might be too weak to take the additional punishment. But after installing a set of SR Performance 1541H alloy steel axles, you will be sure to get all your Pony's power and torque firmly planted to the pavement - where it belongs.Built to Out Perform. SR Performance Axles are forged from premium quality 1541H high manganese steel alloy that is induction heat treated for an axle shaft that is stronger and much more durable than stock, making it perfect for high stress street and race applications.Application. This pair of SR Performance 5-Lug 31 Spline Axles are specifically designed to fit on 2005-2014 GT, Bullitt, BOSS, 2011-2014 V6 as well as 2007-2009 Shelby GT500 Mustangs that have the factory 8.8" 31-spline LSD installed. ABS rings are not included.Application Note: 1986-2004 V8 Mustangs came factory equipped with 28 spline axles, except for 2003-2004 SVT Cobras which were 31 spline. All 2005 and newer V8 Mustangs come equipped with 31 spline axles.