I've been trying to find a 3' exhaust for my 74 Challenger, magnaflow has a complete system for a 72 challenger , the problem is they can't tell me why it won't work on a 74, am I missing something? what has changed between 72 and 74 to the chassis , frame , crossmember , ect . the magnaflow part # for kit is mpe-15852 Has anyone used this kit ? Any info would be great Thanks in advance:4-dontknow::4-dontknow: