Hmm, see I bought this engine...well parts from a guy, the block is a 68' 302 used in a 289 when they ran out of 289 blocks. If the engine is a 68 why wouldn't he just use the 68 connecting rods and why 63? They didn't start making mustangs till 64 1/2 right? I had hoped that other number would give me some insight to figured out if the connecting rods are in some way special IE: HiPo rods -Erik