Looking for a piece of 4" diameter 316L stainless exhaust tubing about a foot long.

Check out metalsupermarket.com. They only charge you for what you need.

That might be the most user unfriendly website I have seen in years. Definitely can't find a 4" stainless tube on that site.
https://www.metalsupermarket.com/

of all things, try ebay. I got the inner and outer tubing off ebay last summer when I extended my stainless marine risers thru transom , I was even able to get the outer tubing polished and it was a LOT cheaper than I expected.

try mcmaster-carr

I buy it off Ebay also. $40 per 4ft. I believe it is 0.060" vs 0.080" good for tails a little tricky to weld.

I have a 4 ft section

Wanna sell half or all of it? Do you mind shipping?

Just checked on the material, mine is only 304 SS. Thought I had 316. Have a 4 ft polished piece new, used this stuff for my 496 exhaust on my 502's.

Believe I have a small piece. I'll take a look tomorrow if you still need it