Description Bultaco Speedo worm drive Pinion Fits INSIDE speedo drive unit on the the front hubs of  Bultaco models- Matador  MK4 Model 75 ,  Matador MK4 SD Model 82 , Matador MK5 SD  Model 107 , MK9 350 Model  140 , MK10 350 Model 210 Frontera 180 , 181 , 214 , 215 , 492 , 493 , Gold Medal Alpina 137 , 138 , 165 , 166 , 187 , 188 , 212 , 213 Part no. 4 in parts drawing below-