Let me tell you what I think you wrote.Front bumper - Rampage
Winch plate (included with bumper)
winch -------- Engo
Question is regarding mounting the winch plate that came with the bumper. Winch plate has standard holes but bottom of plate has countersunk conical holes. Rampage said that conical bolts would be used from bottom up so the plate will sit flush on bumper.
Is a grade 8 bolt available with a conical head???? I would also assume it would have to be a torx so that it could be tightened???
Anyone with similar experience, if so what did you do???
Your bumper and winch plate have pre-drilled holes. The winch plate holes are conical, but not the bumper.
The bolt comes from the underside of the top of the bumper, through the winch plate, into the winch.
I'm assuming there is a locking washer involved as well.
If what I described above is accurate, the head of the bolt is going to be against either a locking washer or a flat washer, or a flat metal surface.
You may be overthinking this.