I recently installed a vintage air system in my 76 vette (originally had air) and now have a parasitic power drain I am trying to trace.  The new AC works great (was definitely a job though).  The drain is a full battery voltage drain at the battery post and have gone through the typical "pull a fuse at a time to determine which circuit" without luck.  The drain is continuous with all the fuses pulled.  I checked at the starter and determined the drain is past that point.  I thought it might be something on the new AC system, but when I disconnect the red power lead and ground at the battery posts and also pull the fuse, I still have the drain.

In tracing my electrical diagram, and looking at all the affected wires against the firewall, I think I have eliminated any external sources.  I pulled the horn relay under the dash to no avail and best I can determine, the drain is either on the red lead into the fuse box or to the ignition switch (or possibly to the light switch).  Everything else appears to be on a fused circuit.  

I think I am going to have to pull out the drivers dash and lower the steering column again (not looking forward to that, but out of ideas).  Any other thoughts on this as to what I might be missing?  The drain is not terrible, but if it sits more than a week, it drains a fully charged battery.  I can easily disconnect the battery or put in a hidden switch, but it is a pain to reprogram my radio every time (clock is not so bad).  The only fused circuits external to the fuse box are on the aftermarket radio and I have already checked that too.

Thanks in advance

I did not mention it, but one of the first things I checked was disconnecting the alternator.  I was getting frustrated enough at that point, I was actually hoping I had a shorted diode or something, but no such luck.

Thx