To those afflicted with "part-number phobia", the original Ford engineering part number is C9ZA-65234A30 (reference the "1970 Mustang Body Assembly Manual" - AM0031 pg 55, item 13 - it's what I have handy) and the Ford service stock number (used by Ford dealers parts' departments) is C9ZZ-65234A30-A (which refers back to the Ford engineering part number so the part can be correctly built and inspected).
(Note: The service stock number say 69-71 applications.)
The two attaching (per side) bolts are 383049-S100.
Without the current revision of the original Ford engineering document for this item, plus any dated assembly line engineering generated variations (based on the variations shown, and, in this case, plant peculiar changes), and dated purchasing records, there is no "guaranteed correct part".
(MCA beware.)
Jim