1971 EV2 Dodge Demon "Sizzler"
Its common for people spread the springs and put a B body rear in. The best way to tell would be to look at and measure the spring perches. If they look rewelded then theres your answer, b body. Factpry welds then measure between the perches and that should determine whether its and A body or B body. Stock A body perch width is 43". Love your Demon BTW!
Heres a link that may help:
http://www.moparts.org/Tech/Archive/axle/17.html