A true "rebuild" would involve several hundred dollars worth of parts, namely about two dozen clutch discs and plates at about $30 a pop. Modifying it is considerably cheaper assuming your existing clutch bits aren't worn out. All the information about doing so can be found in the backyard mechanic and possibly 4x4 sections. I've modified mine already but have yet to install it. I used a slightly different approach than has been used by others so far.