I know the ones you mean, I still have mine someplace from my times at Gatwick in the 70's. Mine came from a consignment of 2380 cases and it might be worth your while contacting the oil suppliers. You never know, you might get lucky. One thing I do know is that they are of little use on the RR B777, makes the can and opener all a bit too clumsy to get in the acess panel but was great for the B707 !