To all rover owners that require a new petrol cap and draw the line at paying $95 from LR for a new locking cap, I have found a suitable replacement. This is to suit my Defender 2000 TD5 and has the plastic large thread type. The Aunger LC91 locking cap fits perfect. The non locking version 91 will also fit. Looking at it it should fit the Disco as well. The guys at Super cheap Kalgoorlie let me get one of the four available and exchange until I found one that fitted. Got it first go. Hope this helps and at $18 compared to LR list price its a no brainer.