HERE IS A NOS GENUINE BUICK PART-SEAL KIT FOR THE REAR OF THE DRIVE SHAFT, FOR ALL 1956 BUICKS. IT IS COMPRISED OF A FELT WASHER/GASKET AND A STEEL RETAINER. I OPENED THIS FOR THE 1ST TIME TODAY TO TAKE THE FOTO. FOUND IN THE MASTER CHASSIS PARTS BOOK UNDER GROUP 5.442 AND PART NUMBER 1392472. SEE IMAGE FROM PARTS BOOK. PROBABLY NEVER FIND ONE IF YOU NEED IT. A MANDATORY SHELF PART IF YOU HAVE A NICE 56 BUICK. SHIPPED GLOBALLY IN A 4" CUBE BOX USPS. THANKS FOR LOOKING