I can't seem to find any tool that will fit inside the holes for the He's and I don't have enough room to slide the bolt not the socket under .

Help !

Do you have the female allen barrel nuts ??
or use a 12mm hex 8mm thread nut ..thin wall socket or turned done in dia.

For all the studs with the heat exchanger tubes beneath them, you should have
barrel nuts. A long allen (8mm?) with 3/8" drive on the other end and you're
good to go. The hard one for me was front right that doesn't have a tube. You
need to bend up a ridiculous angle since the head and the exhaust are in the
way.

They are 13 mn.

I had to put a spacer because my header was thinner than the stock 3.0L exhaust manifold.

Allen Barrel Nut

Barrel nuts like these?

Mine don't look quite that nice. Think about a piece of steel rod, maybe 13mm in diameter and 3/4" long. Hex cutout in one end and the standard 8mm x 1.25 threaded hole in the other.
You can buy a 3/8" drive socket with the hex shaft already attached or make up one yourself by cutting the angle end off and using and 8mm socket.
(wish I was better at drawing...)

As for the ones with regular 13mm nuts, a ratcheting, flex wrench is worth it's weight in gold...

Original style do not have a lip, which would be useless anyway. They are
just the right diameter to go through the tubes.

This is what I have. You can get barrel nuts from Pelican.
Click to view attachment

Typically you will encounter years of corrosion preventing easy extraction, even with the correct tools. Use Kroil or equivalent, perhaps heat from a oxy-acetylene torch and other cutting tools to remove them. Don't apply brute force, otherwise the stud may break at the cylinder head (they might anyway). Be patient. Review the archives on Pelican Parts forum for different removal strategies and tools.

Sherwood

Same tool and setup I have for my heat exchangers. There are also a couple of 8mm nuts on each side (13mm wrench size). I use either a short 13mm wrench or flexible 13mm socket. I was actually able to torque these nuts this time with the flexible 13mm socket. I ran into the same problem with the triad as a previous poster. You have to assemble everything loose with the muffler and then tighten/torque the heat exchangers. I am surprised how much play there is side to side with the heat exchangers.

Thanks .
Rory has some barrel nuts for me that I will pick up sometimes tomorrow.

Put some milk of magnesia or anti-seize on the studs and barrel nuts, it will help when you have to remove them.