Tech 2...

[Alberta Tahoe]

...start probing the wiring at the ignition switch and possibly rule that out, or else solve your issue. Just my 2 cents.

The electrical portion of the switch has been replaced and from I can tell, needlessly as there was no change in the operation of the vehicle. This isn't to say it isn't contributing to the problem but a full set of drawings would go a long way.
Which leads to my next reply...

Now go to ebay and look up "seriousctbuyer" and ask him if he has the service manual on cd/dvd for your truck. Might even have downloadable version too...

I will!

 

[swathdiver]

I also use AllDataDIY which also has most of the same information from the manuals but a little easier to find once you learn how they are set up.

 

[Alberta Tahoe]

I believe that information was mentioned once before but I had lost track of it.
I've just sent off an e-mail to the e-bay seller. Failing that, I'll pursue AllDataDIY.