I didn't read the intermediate posts between OP and here, so beware!

The bellhousing has one hole that doesn't line up, the lowest one on the driver's side. Many leave the bolt out. Because this bolt is the lowest , below the centerline of transmission and crank, it is important to have some clamping force at that point. I found that I was able to drill a new hole and tap it but I could have also used a bolt and nut. It doesn't have to be a huge bolt. It could be one size smaller than the others and still do its job.

R.