I went another way this winter and spring, I had custom leaf springs made. I used Detroit Spring. I had to weigh the truck at each corner using digital scales, then weighed the unsprung weight (axles, tires & wheels, shocks, and anything not above the springs), plus send all the measurements of the leaves. It took awhile to get all the information gathered up. I even checked the old springs for spring rate. Spring weight is the amount weight it takes to compress the springs 1". I had to come up with some small axles and roller bearings, plus a steel plate so there was no drag on the leaf ends when compressing them.
The new springs are much softer with teflon buttons at each leaf end. I am real happy with it and it still sets up like a truck and looks the way a truck should look.
Total cost for all four plus new u-bolts and bushings was $1475. Shipping was $240 of that. To me it was worth it, the ride is just as good as my '03 Toyota, maybe better.