The guys are right about the shop manual. I was blown away at how much is in there and wish I would have bought mine 10 years before I did. I've been buying them from Faxon Auto Literature. They have an eBay store at:
http://stores.ebay.com/Faxon-Auto-Literature The service has been good and I've been really happy with the products. Also, I highly recommend Tom Brownell's "How to Restore Your Chevrolet Pickup." John Milliman wrote a nice review of the book that is available here on the Stovebolt Page.
Some other resources include a Haynes manual for your year of truck (available at any Barnes & Noble) or one of the many good books published by Motorbooks (also widely available at B&N). There is a book by Leo Santucci called the "Chevrolet Inline Six-Cylinder Power Manual" (retails for about $20) that you might like also.
