Bill, that is a part that I supply with my header when a customer is retaining his stock mufflers etc.
This locates the stock heat shield/cover.
There seams to be a few variations as to how Triumph has done this.
First we have a pipe with just a stub welded to it which is (I think) for the earlier three pipe models.
Next we have this.
Then we have this as part of inner heat shield for the Roadster/Touring.
If anyone knows the years/models of these variations, I'd like to know, just for reference.
Possibly the variations are just for more efficient Manufacturing techniques.
For example, that set up in the second photo may have been a more efficient/cost effective production method than machining that stub in the first picture.
The third photo could be am improvement on the previous one.
I for one am always looking at more efficient/cost effective (with out reducing quality) production methods. Interestingly, often more efficient production can actually increase the quality of the unit.