makes more sense why there are two grains on that cut seeing that picture

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.

Yeah, I thought based on what you said that we were probably talking about the same area.

If you can't find it as Tri-tip you can look for Bavette (or bib) as it is cut from the same general area (just don't let them sell you thin flank steak as a bavette)

Tasty!

That small 3rd photo cross section is just about perfection if you are a medium rare steak person!

Agreed. 

Z