Tim1,
Here are pictures of a Curtis blade mount. Back section is bolted to the front so we install as one piece. Front bolts on with 4 - 12mm bolts and the back with 2 - 8mm where the skid plate mounts. These don't have to be as strong because a lot of the pressure there should be straight back when pushing.
The last pic shows the black bar used on 11's for this to mount to, it doesn't mount directly to the frame like it did for my 900. I haven't fitted this since adding the winch, so will know shortly if it fits back on with winch and eyebolts in place. Oh, I lied, the black bar fits on with 4 bolts, this bracket bolts on, with only the 2 outside bolt holes being used, to the black bar. So I quess they figure the grade 8 or 10 bolts are all that is required. Never bent anything in three years of plowing. YET!!!