I started using AutoCAD vs. 2000, I now use 2005 (laptop) or 2007 (desktop).
Most of my clients request *.dwg files in AutoCAD 2000.
 
I've downloaded some useful drawings, in return, uploaded a number (quite a few) of drawings I thought might be useful to forum members.
 
I am uploading in AutoCAD vs. 2000 'cause, I always save to 2000.
 
Open to requests for tank and/or pipe fittings, valves.