rear end for my 1964 dart

just got a lead on an 8 in out of a 1965 mustang will it fit???
64-66 Mustang is 57 3/8 inches flange to flange (wheel mounting). "A" body is 55.6 inches. Not sure of the spring perch. You will need to measure. "A" body perches are 43 inch. Make sure of the bolt pattern. Some 8 in rears had 4 lugs, not 5.