To the OP: NO, you cannot use it on a 383 or 400. It is too wide. If you had a 413, 426 wedge or 440, it would and it would be better than a stock intake, regardless of others' opinions. However, for you, the DP4B is about equivalent. Or a Performer. Actually, there was an exhaustive 383 intake manifold test with more than 10 intakes, find it and go. R.