The advantage of the later model Defender gas cap is the addition of a flexible rubber tether/lanyard that means you can never leave your gas-cap behind on the fuel pump ever again.
Please read!
The Defender Gas Cap Upgrade WILL NOT fit earlier model Defenders fitted with the large filler cap.
It will only fit later models (1998 onwards & NAS trucks) fitted with the smaller threaded style screw-on filler cap.