For your convenience, this nylon gasket will act as a barrier between Defender bulkhead bracket to bulkhead. This barrier will help prevent the two dissimilar metals touching and causing an electrostatic reaction, also will prevent marking your bulkhead. The gaskets are 1mm thick.
1 kit will do both brackets.

Land Rover Manufacturers part no. MXC9983 (Upper) & LR055347 (Lower)