The Samsonas 4 / 5 / 6 (+ reverse) full Sequential Gearbox for BMW F80 M3 F82 / F83 M4 and F87 M2 Competition models equipped with BMW S55 Engine includes Samsonas Motorsport Sequential Gearbox, ACAL RSS Gear Position Sensor, Output Flange, Bellhousing Adapter, and Input Shaft. Bell housing optional.  This sequential transmission boasts Samsonas' X300 clutch shaft, 400 ratio configuration options, quick change top gear, and (5) engagement dogs for maximum fast gear change.  With straight cut gears, racers will notice minimum rolling resistance. Each Samsonas gearbox features super finished, shot-peened gears and internals for optimal quality, and all selectors, shifting fingers, protections, forks, and rods are made from billet steel for maximum reliability.  4-Speed Gearbox Ratios I     2,462     3,000     2,462 II     1,800     2,000     1,647 III     1,471     1,500     1,250 IV     1,250     1,190     1,000 5-Speed Gearbox Ratios I     2,462     2,462    3,000    3,000 II     1,800     1,800     2,000    2,000 III     1,471     1,250     1,500    1,500 IV     1,250     1,000     1,190    1,190 V    1,087    833    1,000    962 I     3,000     3,000    2,462   2,462 II     1,800     2,000     1,647    1,647 III     1,250     1,500     1,250    1,333 IV     1,000     1,250     1,000    1,250 V    833    1,087    875    1,042 6-Speed Gearbox Ratios I     2,462     3,000    3,000    3,000 II     1,800     2,000     2,000    2,000 III     1,471     1,471     1,500    1,500 IV     1,250     1,190     1,250    1,190 V    1,087    1,000    1,087    1,000 VI    962    875    962    875 I     3,000     3,000    3,000    3,000 II     2,000     2,000     1,800    1,800 III     1,500     1,500     1,500    1,500 IV     1,190     1,190     1,250    1,333 V    962    962    1,087    1,042 VI    833    760    962    962