FMT, we're in agreement. I was tripped up by a change in nomenclature.
The cut labeled Bottom Sirloin wasn't called that when I was cutting beef. We cut it into two parts; a roast and stew meat or sometimes a roast and ground beef.
If you look back at what I wrote, "
If you were sitting toward the rear of a heifer you'd be sitting on the sirloin. Well below that, just to the rear of the flank is where I think the trip-tip originates." Just like the diagram you posted.
