i got one of the wheels off a mini finger skateboad and made the hole a bit bigger to just fit the drive shaft and sanded the wheel thiner. that is my spacer for inbetween the two halfs of the truck. then i put it all togeather and saw if there is still enuff drive sgaft for the gear to go on, and if not then just sand the spacer a bit more. after that i squeezed the gear on the shaft and droped some super glue on it, and also on the spacer glueing it to the rear end of the truck. then i melted the drive shaft cover under the truck down to the drive shaft to minimiz wobble. then i just greast it all up. thats prity much it