I checked this out a while ago and as far as I can tell you will have to make them. The only bracket I know of that's commercially built is by Zena, and it's actually a universal setup and quite expenive.
The good news is that the Dodge P/U has a perfect spot for an extra alternator, and the brackets required are actually pretty simple.
Get a hold of smalltiredrat here on the forum, or check out his pictures on cbretards.com
He has a nice setup that didn't require modifying much, if anything...all bolt together, and can easily revert to stock.