[Adger Smith]

The specs that are listed in the NHRA guides may or may not be what was actually produced by the auto maker (all brands). The specs listed are the specs that NHRA Tech Department chooses to accept and publish as "NHRA's Accepted Specification". The acceptance process is usually done by what the auto maker submits to NHRA as the spec for specific engines. I believe NHRA has also altered some specs by what their Tech inspectors suggest or another long NHRA process. In short, What is published in NHRA specs may never be found in a junkyard or stack of engines. On the other hand you may find parts with the NHRA specs.