[bkozlow]

One thing to consider is that the firing order on the old 289 is different, meaning the pairing of cylinders on the left side of the engine is different for the new firing order which the 351 has making the headers different. With the 347 this same thing applies, the new firing order, if used in the 347 requires different header parings. This does not mean you can not use the old style headers with the new firing order, but it will not make as much HP and does change the sound slightly of the exhaust.

Bill K