[89 Cobra LX]

If you're driving around without a header bolt, you're going to find out how fun it is to replace a header gasket real soon.

Any auto parts store should be able to get you a set of replacement header bolts. Just take one of the Mac ones into them and match them up. Replacement headers bolts are a good thing to have on hand. Header bolts have been known to back out. I've actually had one back all the way out on me before and I was glad I had some sitting around when I looked and saw one was missing!

You'll want to periodically check the to make sure the bolts are tight. I would definitely check them every hundred miles or so for the next few months. I've got a couple that will loosen up occasionally.