A disk-seal arrangement for a gas turbine engine rotor includes a blade retention disk having a longitudinally opening slot therein and a seal disk juxtaposed to said blade retention disk and a single anti-rotation tab received within the blade retention disk slot. The seal disk also includes a pair of balance slots disposed immediately adjacent the antirotation tab to offset the weight thereof for preserving rotor balance. A split ring is disposed longitudinally between the blade retention and seal disks for reacting longitudinal loading therebetween. The ends of the split ring seat against side surfaces of the antirotation between the split ring and the blade retention and seal disks.