Dolomite....... for mounting coils, accessories and oil coolers, i’ve had good success using stainless hose mounting clamps. Any good hydraulics shop has a huge selection. If you measure the OD of your frame tubing and find the right clamp (the best ones have a rubber cushion on the inside), you can mount a bolt/nut through the tab hole on the clamp. Makes a supper neat installation, with no modifications.......