Can you help?

Hi,
Im changing the fuel injection pump on my dads 96 300 TDI Auto disco and have a problem. The manual says to lock the fuel pump. slacken the nut off and then take a plate off from behind it. Then you can take the pump off leaving the timing belt in place. Problem is the pump on the car and the new(well old off ebay) pump doesn't have the same type of locking nut as in the manual, I can't see the plate that is supposed to be taken off it. Any ideas? Don't i need to lock it?
Any help would be great!!
Nathan

leave pump as is with drive flange on,dont remove nut,remove timing belt and pulley and change pump that way,

Ok, so if i fit the new pump and use the timing pin it will in the right place???