Quick distribution

Differential output oil seals in NCP10 TOYOTA Vitz were ordered to a private parts distributor yesterday at noon, as for my surprise, they arrived in the evening, whether the stock supply time are all noticed previously on Web site. Probably, parts supply network of domestic automobile manufacturers must have been developed enough to refines. Disassembling of knuckles on both side would be required to remove drive shaft from differential gear box. Do I do this by myself or ask to the professional factory?