Well, my ignition lock failed so I spent some time and took everything apart and got the new one in.  I thought I got everything put back together right, but when I hooked up the battery, the horn came on and stayed on.  My '76 has tilt/tele and of course everyone knows that '76 is the bastage child when it comes to the steering wheel.  No parts available in the catalogs and the diagrams/instructions in my Haynes manual do not match up very well.  Any thoughts about what I did wrong?  Taking the horn button off and the actuator parts underneath it did NOT solve my problem.  Taking the steering wheel off does, however.  I hope whatever I did wrong is above the locking plate (that locks the steering wheel) because that thing is a P.I.T.A. to get back together.   Any help would be greatly appreciated! 

If removing the horn contact plate doesn't solve the problem, then I'd think you've managed to pinch, or otherwise ground the horn wire. The plastic horn contact ring that goes underneath the lock plate has to be oriented so the tower for the little wire/button fits thru it in one location.
I think I have a couple of diagrams of the column...I'll look and see. If not, someone here may have some pics...

THIS may help...the '76 ain't much different...
Adams' Apple2009-06-30 05:17:27

Thanks Joel.  You're probably right.  I'll take the C-Clip and locking plate off and inspect.  It's not that hard - I just had to have my wife slide the C-Clip on while I was pushing on the locking plate.  She knows how to do it now.  

I figured out what's going on here.  When I took the whole ass'y apart I forgot that I broke a small, extremely brittle plastic piece that goes over the C-Clip.  I figured it was an inconsequential grease or dust seal.  WRONG!  It's what prevents that spring behind the steering wheel from permanently completing the circuit between the horn contacts and ground.  Very necessary.  Note that I don't think this part is used on pre or post 76 models.  It might be used on Vegas or Camaros from the same era that have that goofy steering wheel.  Well the parts catalogs I looked at didn't have it so I wasn't sure what to do.  Lo and behold, I went to the local Chevy parts counter and the guy pulled up a diagram and we figured it out.  Still available, just had to order it for $15.  Kind of expensive but it beats the alternative of scrounging around a junk yard for another really old brittle piece of plastic.  I don't think I could have possibly gotten mine off without breaking it.  I just touched a screwdriver to it and it crumbled.  I'll post again after I get the part and install - just to "complete the circuit"