Trying to get the main bearings out to replacebut the last bolt seems to be busted at the head. Any ideas on how to get it off? Main issue, knocking in the engine and oil light is on, replaced the lifters and the oil pump now trying the bearings. After cleaning the other bearings off, its a copper color, does this mean they are worn down?

PS I took it to Arlington Motor Car in VA hoping they could tell me the exact knocking noise is, no help at all, said it was the oil pump, not, it was just replaced. So $98 later, still have no clue what the noise is. HOPING it will be the bearings.

 

98Discodriver
If the bolt head is rounded out, you can get a " bolt extractor ". Sears sells those. If the bolt head is sheared off, a bolt shaft extractor is also available. One type looks like 2 round plates with a hole on one side for the bolt shaft, the other type is like a socket with teeth. This socket has to be hammered on to the bolt shaft.
Sorry, no experience with the main bearings. Bearings shouldn't make a knocking sound. Since you have the oil pan off and changing the crankshaft bearings, get a peek at the cylinder/liner from the bottom if you can and examine all 8 cylinder/liner. Look for signs of a slipped liner. Knocking noise in the engine could be a lot of things. Lifters, rocker arms, slipped liners, to name a few.
However, with the oil light on, lifters/rocker arm noises from insufficient oil pressure would be likely but not definitely.
Ed