tti headers for small block

Regular part numbered TTI headers come in 1 5/8"-1 3/4" step or straight 1 7/8".
(I forgot if they advertise the ID or OD. :( )
A part # would help ID them and any internal/external coating options.
(Just noticed the box #.)

But I have the 1 5/8"-1 3/4" stepped versions on my car and they work very well.

The box part # is for straight 1 7/8" W-2 race head headers. The headers shown appear to be the 1 5/8"-1 3/4" step for standard heads.