Howdy Mike,
I just installed one of these in my shop to make better use of wasted attic....
http://www.wernerladder.com/newprods/s2200.php
It is the unit that logical mentioned.
As he said, I've not seen a double wide unit that was not homemade.
I thought this ladder would seem aweful narrow as I plan on hauling some fairly large things up and down it.
I find that the size of the ladder is fine. It is well constructed and a whole lot more stable than the wooden version in my old garage. The handrail on the aluminum one is nearly nonexistant.
I had some difficulty pushing large items ahead of me and finding that little rail at the same time so I rigged up a rope and pulley sytem.
Now I just tie onto whatever is going into the attic, get in the attic myself and haul it up, then swing it over to the floor once up there.
Beats falling over backwards and having whatever I was hauling remind me that I just fell over backwards!
Hope this helps.