Can anyone tell me a website that will give me the ignition wiring diagram for a 91 silverado

Haynes Manual

convertedchevyman the forum for the older trucks is here:
http://www.automotiveforums.com/vbulletin/forumdisplay.php?f=1453
You might have more luck but I think the best place would be to go to a local parts store and get a Chiltons or Haynes manual.