i have recently bought a factory alloy bullbar and am having trouble installing it. i took off the bumper and tried 2 put the bar on, but there is no mounting points. the bar came with two steel plates each with 4 threaded holes, and they fit into a rail in the back of the bar. it is a different mounting to the bumper and there is no place to bolt it on, do i need another bracket that bolts onto teh chassis in place of the bumper brackets? or do i need a bracket to go on the bumper bracket?