8 3/4" ring & pinion is the weak link. Then the cap. Not sure where 30 spline race axles fit in, but I've run 35 spline 1/2" screw-in stud Moser axles for many, many years without problems. - 360/904 footbraking @ 3,540+ lbs running mid-low 11's averaging 1.52 60' times. Combination of weigh with good traction & 60' times cause the most problems. Never broke a cap, but there were signs of "cap walk".)