Take your shocks off and go for a slow and careful cruise through a familiar area. If the truck is still harsh feeling, then the problem stems from your leaf spring setup or spring rate. If the harshness is gone than you know it is the shocks.
For sale of discussion I am going to assume you both have King 2.5" Prerunner Bypasses. Standard off the shelf valving that King suggests with leaf springs is .015 on compression and .008 on rebound. I would start there. To help improve ride quality you can as flutter shim on the compression side, or change out the compression poppet for one with a bleed hole. If it already has a bleed hole, you can try drilling it out to a slightly larger size. I would do that in baby steps rather than drilling a big hole in it because too much bleed is a bad thing.
Speaking from my own experience here, I could never get my 2.5x16" King Tripples to work correctly on the back of my ranger and I believe it was due to the bypass tube size. I changed shims a few times from .012 to .015 and tried a mixture of them together but I ended up selling them and getting 3.0" race series 5-tube shocks, and those are hands down the best thing I ever did to the truck. They flow a lot more due to the bigger bypass tubes and were smoother through everything. There were many times that I came up on stuff way too hot and those shocks soaked it up, where as I know the old 2.5"s would have killed me. Overlapping tubes are key on leaf springs.
Sent from my iPhone using Tapatalk