Recently picked up a couple of case cover drains that came off an early serial numbered GTR.....#52.
Pictured below is a comparison of the early drains (left) vs. later drains (right) from both the GTR's & GTO's. Neither look like the tube drain pictured in the parts manual. (last pic) I've seen pics of the tube drain and it looks nothing like these two, its pretty much like what's seen in the parts manual. Not even sure how it attaches to the case covers.
So there ya go........ wonder how long BS used the early drains before switching to the more common ones?