Here are a number of sources for fabrication parts that I have located over the years. These manufacturers offer many of the tabs and brackets that save a huge amount of time when you are trying to build something, many of which are priced a lot cheaper than what you can make them for.
These are not vehicle specific per say, though the manufacturers list different vehicle specific applications.
p://www.ballisticfabrication.com/
http://www.bluetorchfab.com/store/
https://id211.chi.us.securedata.net/independent4x.com
https://id211.chi.us.securedata.net/....php?cPath=127
http://www.sky-manufacturing.com/
http://www.blueyfab.com/
http://www.hrpworld.com/index.cfm?form_cat_id=310
http://www.speedwaymotors.com/