All 4-speed cars should have rears, most automatics had none, unusual to see and automatic with rears. I have owned over 50 performance A-Body's over the last 42 years and only the 383 automatics had rear torque boxes, but not all of them. Torque boxes were much more common AFTER 1969 from what I have seen. Of course all convertibles had front and rear boxes. What engines does your have?