Matching Numbers

[jaybirdk5]

Tried looking at past posts and still have not come up with definite answer regarding matching numbers.Some posts I have read say the factory did not stamp matching numbers on engine block. Is that true? I have a 69 Blazer being restored and the numbers on the block are a manufactured 69 block but do not match. I have read in posts the correct number would be stamped on protecto plate but mine was not included with the blazer when I purchased it. The blazer seemed to be all original except for the rally wheels. Any input would be appreciated!