I did about what you have now in terms of height, but I fastened the boards to my riser. 3″ should be plenty. I do not think you will have a problem. I can’t tell you whether others had an issue. Ford cabs are much taller than Dodges and since NorthStar offered the riser (basically a 2×2 soaked in creosote) I thought it would be enough added height. I was wrong! 🙁
Steve and Andra
2012 F350 6.2 gasser SRW LB
Fab Fours front and rear in case we run into a rhino
2019 Northstar Laredo SC
