Thanks; on my cover all the holes are the same depth. I found a 200 six in a salvage yard and I am going to look at it today. I will get some of the bolts from it, too.
I have four bolts which are about 1/4 inch longer than the others, and I need four bolts to finish installing the cover, which seems to be telling me that these are the bolts, and I don't understand where they go, or that something else like a bracket fits underneath the heads. I know these four are about 1/4 inch too long for any of the threaded holes except the one near the oil filter which is drilled and tapped all the way through. The head styles are the same with an integral washer forged onto the head, so they are not off-the-shelf bolts added later, and they are all for a 3/8 in wrench.