If you are looking for a cathedral port TBSS/NNBS manifold and the seller only has pics from the top, it is pretty easy to tell the difference now that I have them side-by-side.
The bottom pic shows that the injectors point into the "attic" of the cathedral.
The top pic is square ports.

 

What part number injectors are those on the rectangular port

 

Not to mention fuel rail bolt placement tbss/cathedral port/4.8/5.3 are inside rails, the l92/ly6 are outside....

 

Some sexy OE LS manifolds tested here...

20 LS1 Intake Manifolds: Tested!

 

I know. That is the December Hot Rod Magazine article that made me buy a new used manifold. I originally installed a Vic Jr because internet hype suggested everybody was melting their number 7 piston because the truck intake manifold was imbalanced, sending too much air to the rear cylinders.

 

So this dyno test in the magazine shows that the TBSS manifold gave 50 more horsepower at 3500 rpm my Vic Jr. I hope the results aren't way skewed because they had a carb on the Vic Jr.
Anyway, magazines are the devil.