Some fuel filtration, and some gauges sounds like a good next step...What do you want to do with the truck?
Also, did you see this thread: http://www.cumminsforum.com/forum/3rd-gen-performance-parts-discussion/580810-basic-supporting-mods.html
Also, did you see this thread: http://www.cumminsforum.com/forum/3rd-gen-performance-parts-discussion/580810-basic-supporting-mods.html