['ol Pinion head]

The addition of the drain fitting was a later in the model year addition. A late May Arlington built '70 Judge has been the earliest I've run across that was an original car which had the hood tach drain set-up. That particular Judge dud not appear to have been taken apart & have had the inner AC box replaced. Replacing the inner cover due to damage with a nicer used one, as well as replacing non functioning suncooked hood tachs was very common. Over a dozen years ago, before the BB crashed, i posted from time to time on V8buick.com. There was a good discussion going onnthat board about original hood tach usage, & I can remember contributing to the discussiion. The longtime Buick GSX preservation/restoration guys gave the opinion the Buick hood tachs with the drain fitting & hose setup did not arrive on cars until the '71 model year. Pontiac obviously was installing their version earlier & a reason I asked the question whether in original 70 GSX's were built that way.