Alcans are the best quality springs for the money. Also, custom suspension has 2" parabolic springs but they cost a little bit more than alcans.
Skyjackers are about half that of Alcan but you will be much more happy with alcans because they will last much longer, made of better material and ride smoother. Alcan builds to your specs too. I just bought a pair from them that are 6" of lift to my specs and vehicle modifications (everything from the addition of a 2nd battery to heavier off road bumpers). Alcans were $550 shipped to my door and they take about 3 weeks to show up and are available in stock or any lift height you want.
Skyjackers are around $250 a pair last time I checked. NEVER BUY ADD A LEAF springs for these trucks. They are dangerous and will wear through the top spring leaf and cause the spring to fail.
If you are Mr. Lowbuck which is nothing bad, I have done a junkyard conversion on my last truck using 3/4 ton leafs from a late 1960s dodge pickup. They have one more leaf, military wrap (keeps the leaves from negative arching as easily) and ride smoother than stock. Install poly bushings in these and you will have a more level truck with a better suspension ride up front.
It all depends on how long you want to keep it, what your roads are like (anythings better than PA roads!) and what you have for tires. A 33" tire is about the biggest you want with stock suspension. Read Alcan spring's website to learn more about spring styles.
Alcan spring:
http://www.alcanspring.com/Custom suspension:
http://www.customsuspension.com/store/p ... ts_id=1861New diesel stock spring on left, junkyard leaf on right. Military wrap seen here on the junkyard spring eye (right).
Junkard spring seen here still has 3/4" of positive arch. They stayed like this for the 5000 miles I drove it before I sold the truck. The springs are OEM factory so they had plenty of miles and were well broken in so I knew they wouldn't settle any more as I drove it.
New stock on passenger side, late 60s dodge on drivers:
Charlie