Iraggi, DC Power, HO Alternators are some brands...
http://www.highoutputalternator.com/index.htm
I would search on google just to see if you can find a good one for your truck. The brand shouldn't necessarily be your primary concern at first. Find one or a couple for your truck and then check out the brands to see if they are good.
One important thing to look at when choosing an alternator is their power output at different RPMs. The output from the alternator is going to be less at lower RPMs so you need to know not to just look at the max output rating. That rating could be at a much higher RPM then you typically drive at which means the actual output of the alternator is much less then you need.
When choosing an alternator it is better to go big. There is not going to be a problem with going too large other then the added cost. Just make sure you get a big enough alternator or you may not fix any power issues you may be having.
Good Luck!!!
