Depends on which 390 intake you are replacing. The C4 and T manifolds have a carb height of 4.06". The S manifold is 4.75", while the CJ is 5.06". Carb setback is identical on all four of these manifolds. You might be able to use the same rod if you currently have the S, but if you have one of the others, chances are you might need a new one. You can contact Kickdown Rods Galore and More and they can tell you. He can custom-make one for you, too. Their customer service is top-notch, highly recommend them.
