For help choosing components I joined the Fox Valley Electric Auto Association. There are lots of electric car clubs. This one dedicated to promoting e-cars and supporting it's members in building and owning EVs, has interesting members, informative meetings and newsletters and fun events. It is located in (what else?) the Fox Valley west of Chicago.
Also available on-line is the Electric Vehicle Discussion List with loads of very knowledgeable contributors.
The suppliers I used also sell "how to" books, tapes and CDs and offer engineering and design consultation. They will give no charge advice on products they sell. Their sites also feature conversion packages or kits that list components suitable for cars/trucks of various weights and driving expectations (speed, range).
Though not listed as links, these sites (and many more) are easy to get to.
Fox Valley Electric Auto Association (FVEAA)
Electric Vehicle (EV) Discussion List