depends on what your after....full tile the "best" thats on the market right now is the giant link killer...be close to 3gs but the time your done with shocks and the springs kit.
deaver's "pre runner" spring f31 I think if the part number, is the dailt driver weekend toy spring. byy the time you have it all set up run you about 2g's springs, shocks, shock mount/bed cage
deaver race pack, g50 is just that the race pack, set up if your going to run a large fuel cell, dual spare tires run about the same as the "prerunner" pack by a few hundro more.
National. spring co, is trying to make a come back from what I understand with new owners and better bussines ethics, since the lase time I dealt with them on springs,and making custom spring's to fit your needs.
But first I would find out what you have on the back of your truck now.
how many leafs do you have in your spring packs?
is the shackle fliped allready?(search on this board you can find out what I mean)
and do you have any pics?...that could help us alot to tell you what you have, and what you may need.