Yes I am running Marlin 4" USA springs all around. My front springs are PERFECT. I can go over parking lot speed bumps at 15 MPH with little jarring until the rear hits.. Those tires get straight-out launched!
![Ack :ack:](https://board.marlincrawler.com/Smileys/marlin/ack.gif)
As for my shackles, I like to run them loose, quite loose actually. But, you are right, now that I don't need to do everything to help the springs twist (since they won't be twisting anymore) I can run my shackles tighter without preventing spring operation.
![Thumbs Up :thumbs:](https://board.marlincrawler.com/Smileys/marlin/thumbs.gif)