Check your gap between stop and frame...probably can barely slip your index finger in up to the second knuckle....
The Timbrens will soften that inevitable blow, but the only thing that will change that is new springs or at least adding a leaf. But you've still got old, tired non greasable bushings and new springs supporting fatigued ones......
I tried the stops first, then Ranchos....finally got new springs from Goanna Tracks w/ the greasable shackles......couldn't be happier....brought the truck up about 2.5", sits level. Simple installation. If you're in the States, Tony has them up in Calgary....