Standard equipment was a 351W 2V Windsor motor with a 3 speed manual transmission, and a 9" 28 spline open rear axle. A 351W 4V was optional as was a 390 4V, and the huge 428 4V Cobra Jet or with the "drag pack" option, the 428 4V Super Cobra Jet. A 4 speed manual or 3 speed FMX (small block)/C6 (big block) automatic transmission was optional, and the 428SCJ added a cast iron tailshaft in place of the regular aluminum one to the C6. A "traction lok" rear axle was optional, and the 428 CJ/SCJ included a "traction lok" with a 3.91 or 4.30 ratio, 31 spline axle shafts and a nodular case. In 1970, the 3.91 ratio was a "traction-lok", while the 4:30 ratio was a Detroit locker. Mach 1s came with upgraded suspension to varying degrees dependent upon powertrain choices. Big block cars had front shock tower reinforcement, thicker sway bars (no rear bar for 69), and heavier springs and shocks. 428 CJ/SCJ 4 speed cars also came with staggered rear shocks.