Great job, TM. Looks like you had quite a feast. Definitely calls for a like.
Where I am (Chicago), the cut goes under a few different names; top sirloin cap, rump cap or cover, coulotte, or picanha. Whatever name may be used, the NAMP number for all is the same. For roasts that run around 2 1/2 to 3 lbs, which is what I always get, it's 184D. If it's cut and sold as steaks, I believe the number is 1184D.
The only distinguishing factor between the picanha and the others is that the picanha is always left untrimmed of the roughly 1/2" fat cap. Both the coulette and picanha are very tender and extremely flavorful cuts of beef, but I think that the fat on the picanha adds another level of beefy richness to the flavor. No matter how it's prepared, it's our favorite cut of beef.
In addition to the U.S., I've had picanha in Brazil, Argentina, and Uruguay and tend to prefer the South American beef over that from the U.S. as the better quality beef in South America is typically 100% grass fed.
Voce cuida, tambem.