The receivers built into bumpers are usually not rated for towing. THey are for recovery purposes. I think there are a couple bumpers that actually are rated, but I don't remember which brands. The bumpers usually don't have provisions for hooking up the trailer's safety chains either.
2004 Wrangler Rubicon-Solar Yellow, auto, air, dual tops.
2" BB with DT 3000s, Homemade discos, Hella 500s, air horns, Okole seat covers, "custom" pinstriping
[COLOR=yellow]Yellow Jeep Club and Redneck Jeep Club member #666 [/COLOR]