SAMWEL'S TRANSMISSION KITS FOR 45CI MODELSComplete set of gears to convert an existing 1941 1973 style 3 speed transmission in a smooth shifting and reliable 4 speed. Fits in the genuine transmission housing with minor modifications to clear for the new first gear. Also requires small modification of the transmission door or the separate purchase of our ZPN 235263 side cover. Features drop forged gears for extra strength. European made quality for your good old seven fifty.