Brian, according to "The Hollander", all the 351C shared the same radiator, however there were some different part numbers for the years and the size of the radiator.
The Hollander shows the following part numbers for certain 1971 - 1973 Mustangs, Ford passenger, Lincoln , Mercury, and Montego with the 351, 400 and 429 engines:
D2AZ8005D - 1 1/2 inch thick
D2ZZ8005C - 1 1/2 inch thick
D3ZZ8005A - 1 1/2 inch thick
D1VY8005A - 2 3/4 inch thick
D2AZ8005B - 2 1/4 inch thick
D3ZZ8005C - 2 1/4 inch thick
Based on the above, I would think that the "correct" part number for a 1972 Mustang radiator would be D2ZZ8005C.
BT