After going through all kinds of trouble trying to find the right parts for my truck and finding places to buy them I have decided to share what I have gathered so far. These are the websites that have made this project a little easier, I also suggest you get a GM parts catalog for your truck it will make it easier to find the correct part.
http://www.finditparts.com/This is where I have ordered most of my hard to find parts, they have good prices but you will need to know what part number you want because they do not have a catalog you can search.
http://www.truckpartsinventory.comHere you can enter a part number or short description of what you need and it will show you who has that part. This has been a huge help for finding very rare parts.
http://midwesttruck.com/catalogs.htmThis site has many different catalogs where you can look up part numbers.
http://www.raybestos.comClick catalog at the top and here you can find the brake parts for your truck.
http://extranet.soleniuminc.com/centricparts/Here is another place to search for brake parts.
http://fme-cat.com/Here you can find digital catalogs and cross reference/part number look up for all federal-mogul divisions.
http://www.meritorhvs.com/MeritorHVS_Documents/PB8951.PDFFront axle parts catalog
http://www.showmetheparts.com/timken/#This is timkens online catalog where you can find bearings, races and oil seals
http://www.dsuban.com/website_docs/Hayes_Lemmerz_Catalog_02-03.pdfHere you can look up or cross reference wheels hub and drums for your truck.
http://wellertruck.com/lit/Weller_Diff_Catalog_2011.pdfThis is a differential catalog where you can find all the part number to rebuild or re-gear your differential.
http://vexer.com/automotive-tools/speed-rpm-calculatorThis will let you test different gear ratios for your truck.
http://gmheritagecenter.com/gm-heritage-archive/vehicle-information-kits.htmlHere you can get a catalog with the original spec for your truck.
This is all I have for now but I will update it as I find other helpful places. Feel free to add your own links in here and I will add them to the first post.