Ok I donÆt mean to be a smart a$$ with this response, but what does your repair manual say? I would imagine it would have a length for your engine? I honestly don't know though. But thinking about it logically, all of your intakes should be the same length, and all of the exhausts should be the same length, all 12 could be the same length too. I wouldnÆt take too much work to pull them all out and lay them up side by side in order to see if there are visual differences.