Here is the the set for the Discovery II from 2 good places to buy.

British Atlantic:
I think these are after market to but many people on the forum have used this kit with good success


Head Bolt Kit

Rovers North:

Proline brand (decent after market)
http://www.roversnorth.com/store/p-1...t-kit-v-8.aspx

Genuine Land Rover

http://www.roversnorth.com/store/p-1...t-kit-v-8.aspx