don't know about wheel alignment for trucks, but for aftermarket truck toys you can try "the truck stop" in sayville on montauck hwy, or theres another place in sayville right next to sayville ford( forgot the name, but just before dealer). hope this helps.
For the alignment try Kreskies (sp) on Montauk hwy in Bellport. Honest and does good work. 4WD shops in addition to what Jeff said, RMS off road on ocean ave in Bohemia, TNT conversions, Tower conversions are all decent shops.