I used the small bracket that came with the Warn winch. Wow that was tough,lots of modifying. Should have waited until I had the right parts. I'm assuming the winch is still just as tough. I used 3, 1/2" bolts right to the frame. Isn't that where the winch plat would have bolted to as we'll?
I mounted a Badland 2000LB winch to my 550 S4. I wanted a little beefer bolts so I went from 3/8" galv to 1/2" stainless. I had to drill out the holes on the braket and the holes on the plate behind the front bumber to except the bolts. I ,also, had to extend the wires to reach the battery. It works great. I also went from the 3/32 wire cable to 3/16 synthetic rope. I read the specs on the 3000lb Badland and the only difference was the size of the cable and the speed. Anyway it works great on my 1440lb vehical. Winch was $79.99, mounting plate $3.95, and the 3/16 synthetic rope (5800LB 50') $79.99. I bought the winch and mounting plate from Harbor Freight and the synthetic Rope from Amazon.