Issues with the tooling . Apparently , Round2 was going to do with the 1971 Demon what AMT (et al.) did with the 1970 Super Bee in the 90's :: "bash" it with newer tooling ; to wit : MPC 1971 Demon 340 body (etc.) with the c.1998-issue AMT 1971 Duster 340 (chassis , engine , etc.) . I'm willing to bet that , since the MPC A-body series (1971-1975 Duster , 1971 Demon , 1975-1976 Dart Sport) tooling is every bit of 40 years old , that it's too fatigued to rework . Remember that Round2 was going to take the 1975-1976 Dart Sport tool (which has been reissued and reworked a few times since its retirement as an "annual" at the end of 1976) and backdate its body to 1971 cosmetics (no small feat !) . Perhaps Revell , Moebius , et al. , could do it better vis-a-vis all-new tooling ... (and , no , I'm not knocking Round2 by stating that)