When the 1972 Road Runner/GTX was introduced to the public {September 5, 1971}, the 440/290 HP 'U-Code' with the Air-Grabber {Fresh-Air Package} was re-factored to 330 HP by NHRA.
The car was factored with a Weight/Horsepower of 11.14 Wt/HP which put the car in I/Stock {11.00 to 11.49} for the late-1971 Racing Season.
In 1972, the NHRA went back to 'near' Pure Stock for Stock Eliminator and changed the Class weight breaks.
In 1972, the Road Runner/GTX 440/290 HP {NHRA; 330 HP} was classed in C/Stock {11.00 to 11.99 Wt/HP}, or in Super/Stock 'SS/K' {11.00 to 11.49 Wt/HP}.
They did very well in C/S and C/SA.
Eventually the 1972 '440/290 HP' was re-factored to {NHRA; 345 HP}.
Now the 1972 Road Runner/GTX {440/290 HP} is factored in at {10.65 Wt/HP}, and is now classed in F/S or F/SA, or in Super Stock {SS/J or SS/JA}.