Peace, mercy, and blessings of God be upon you.
I have Land Cruiser headers, manifold and downpipe without the last muffler (sold). They were removed and I had them on the roof for 10 years and just took them down. I don't know about leaks or welding. They were removed from a car before I sold it.
Selling for a good price, just give the part its due.
Contact via private message or call is better.