FOR A '72 RUNABOUT 6.75 AXLE,THE PINION SEAL IS NATIONAL SEAL #8181NA .THE AXLE SEALS ARE NATIONAL SEAL PART #2669.FITS BOTH SIDES AND ARE DISCONTINUED.T HERE IS AN OLD PARTS STORE IN TABOR CITY N.C. THAT HAS 3 OF THE AXLE SEALS ON THE SHELF AND WILL SHIP.DYRELL'S AUTO PARTS,PH# IS 910-653 4129.THEY ARE A TREASURE TROVE OF OLD PARTS I'VE USED THEM MANY TIMES ,GOOD PEOPLE.I GOT THE SPECS ON THE SEAL AND THERE IS NO OTHER SEAL THAT MATCHES.