ET - your friend may have been talking about this. I've used it and had success. The big trick is making sure your exhaust pipe is properly lined up to the manifold. It often takes a bit of juggling, bending, jacking, tweaking and cussing to get it right. A sleeve or gasket won't compensate for improper alignment.
https://www.macsautoparts.com/catalo...haust%20gasket
As 1crosscut says, you can also use muffler cement (like
https://www.permatex.com/products/sp.../?locale=en_us) between the exhaust pipe and manifold. If either of them have significant pitting or rusting this might be the thing. Again, cleaning of the mating surfaces and alignment are critical.
JayJay