Well, I finally found the block #'s on my 83 L69. Here's my question, it's on the numbers that I found on the deck tab behind the altinator. I have been told that if this engine was rebuilt that these numbers are machined away? I have been worried for the longest time that it wasn't the original engine seeing it was beat to sh*t and only gives a puff at start up. After finding these numbers I am amazed and relieved it's original. If they do machine them off is it possible that even after a wire brush, degreaser, etc that it was very faint and hard to see because they machined it some? I am going to sand blast em at some point. Any insight as to what is done on a rebuild and if I will loose them when I have it rebuilt? I don't want to loose em seeing it's in the total restore process. Sorry so long. Thanks!