? Replaces M-7003-R58 ? Gear ratios starting with first are; 3.27, 1.97, 1.34, 1.00, .68. ? Features improved shift forks, 1 piece counter shaft, gears made of 4615 steel which increases the torque capacity over that of the M-7003-R58 model. ? Input shaft is 10 spline 1.0625 and the output shaft is 31 spline. ? Requires a unique bellhousing M-6392-R58 to install in a 1979-95 Mustang ? To fit in a 1979-93 Mustang use M-5059-A crossmember. ? To fit in 1994-95 Mustang, modify vehicle crossmember,lengthen driveshaft .625'' and use clutch fork E6ZZ-7515-A ? 31 spline driveshaft yoke required ? Can be used in 4.6L applications with bellhousing M-6392-M46. NOTE: specs & photo may vary