If you're using OEM headbolts, yes, they're supposed to be replaced any time the head comes off. If you reuse your old bolts, they may stretch and your head will lift which will mean the gasket won't seal. I forgot to order headbolts when I changed my headgasket back in September, and now I'm getting some coolant seeping out from under the distributer. Needless to say, I don't want that happening again, so I ordered some ARP studs this time. You should be fine with new OEM head bolts though. They should only run you about $20 total for the set, maybe more if you're going thru a dealership. As for the two bolts that are different, I'm not really sure what that is, since all of my Y8 bolts are identical.