Rich, Thanks for the excellent instructions. I've been putting this job off for quite a while. However I found it to much easier than you describe
On my '85 380 SL all I had to remove was the exhaust manifold heat shield. I then used a breaker bar with extension, wobble/universal adapter and 19mm deep socket. I easily loosened the outside nut. The hex bolt moved along with it. After removing the socket I reached under the manifold with a 19mm open end wrench (approaching from the front of the engine). I positioned the wrench just enough to get hold of the outside nut...just enough to allow me to loosen the hex (allen) bolt without moving the outside nut. Using a ratchet, extension and hex head socket (no need to cut an allen wrench) I carefully loosened the allen bolt. Then I tightened the outside nut with the 19mm socket....worked like a charm. Also, the allen bolt loosened easily. Perhaps beacause my car has always been garaged. I didn't need to use PB Blaster..phew.
Below is the type of hex head socket I used. I've had a cheap set for many years and they come in handy quite often. Harbor Freight sells sets for about $7.
Thanks again...a 3/4 CCW turn got my steering back to perfect.