WTB: test pipe for stock down pipe for ‘87 GN

Anyone have a test pipe to fit the stock down pipe for my ‘87 GN? I think it’s 2 1/2 inch. Prefer without the side cut out.
Thanks in advance!!
If all else fails www.kirbanperformance.com has a 4 bolt flange if you end up making one.

I thought they use to carry 2 1/2” test pipes for the stock downpipe, but I couldn’t find it.