Only these models have the correct LENGTH ON the stater side of the crank which is longer than the auto models to work with this CDI unit conversion kit. This kit also has the smaller taper in the flywheel to work with the old points type crankshafts. I highly suggest getting the sub-w-1212-66 the six volt regulator rectifier and sub-w-1 listed below on this page @ CT70HK0_HK1 SL70_XL70 CDI_CONVERSION_KIT (400072) exed sorry discontinued 400072 @ BOTTOM VIEW OF 400072 @ 12V_or_6V CT70 REGULATOR RECTIFIER_PIGTAIL CLICK FOR_INSTRUCTIONS (SUB_W_12/12/6/6) (S1255) SUB-W-12/12/6/6 (S1255) @ 6_VOLT REGULATOR RECTIFIER CONVERTS_12V CLONE_ENGINES TO_6_VOLT!! KEEP_ORIGINAL LIGHTS_BATTERY (6V_reg_rec) (S1249) 6V/reg/rec (S1249) @ e ENGINE_SWAP_WIRING INSTALLING_A_CDI ENGINE_IN_POINTS TYPE_BIKE CT70K0_to_76 all_Z50A_MODELs (SUB_W_1) (S1256) (SUB-W-1) (S1256)