Hey guys, thought I would share some recent photos that Joe917 was good enough to send me. Now I think I might have a plan on how to mount the AC compressor. From what I see in the pictures it looks like MB had 2 different front engine "cradles" (the beam the front of the engine is bolted to, then that beam is bolted to the engine mounts). Below is the picture from Joe, this picture was taken looking up from underneath the truck, the oil pan is the upper left so the mount is just in front of the oil pan.
Now this is how mine is setup.
Slightly different angle with the picture but for some reason we have a cross brace that is not in Joe's picture (the red one on the right). You can see the pulley that Joe's AC is belted to right between the "cradle" and the cross brace. So it looks like to make it fit I would need to modify both of these bits. The cradle would be removed and the AC bracket bit fabricated and welded on (or maybe a complete new one). The cross brace would need a bit of massaging to get enough space for the belt to get by. I guess this is why the thought never occurred to me that this was where the factory installed it, but now makes sense. Thanks Joe.