OK. Here's the story. I have pulled many engines apart over the years and I have seen some that were sealed VERY well. There are three different types of sealants that I have come across that I am trying to figure out what they are. I *think* that Indian Head shellac was one of them.
Basically, two sealants (one brown, one red) were almost like glue. Very strong and sealed very well. Indian Head may have been one of them but I do not know what the other was. It was NOT red high-temp rtv sealant. This was a dark red substance that was like glue.

The third was a gray sealant that was more like rtv but much better. Ultra gray, maybe?

Any ideas?

Thanks,
Stan