Turbo 400 Billet Steel Forward Drum and Heavy Duty Input Shaft. Drum is machined from 4140 HTSR billetsteel. Input shaft machined from 300 Maraging. Shaft to drum spline count has been increased from 30 to 35 splines for extra contact and strength. Overall drum & input shaft weight is2.50 lbs lighter than the OEM drum & shaft with major weight reduction on the O.D. The input shaft is permanently located in the drum by a shoulder stop and snap ring.