According to Frank Badalson of
www.rogergibsonautorestoration.com in the June 2013 Mopar Collector's Guide:
1970 - 1972 E body shackles are 4" c/c, and 1966 - 1972 B body shackles are 3-1/2" c/c. Other dimensions, fasteners, and bushings are the same. The E body shackles from Mopar Performance are incorrect in all dimensions and finish, as well as the supplied fasteners.
Contact Frank for the correct 70-72 E body shackles and fasteners at the link above.