Flaming/sparking out the right rear

Okay I was driving my 05 excursion today and as I went to get over to the right I noticed dark orange flaming debris coming off my ride. It looked like I was dragging chains down the road. I put the trans in neutral and the truck idled normal, I coasted to a stop (took a very long time to coas to a stop) and got out and looked around. No signs of anything? Drove 40 miles regularly and noticed nothing. Are there any common problems that occur on these that cause something like this? Cat melting and flying out the exhaust? Rear axle seals leaking on brakes and catching on fire? Anything any one can think of? FWIW I was at about 3700 rpm in over drive WOT for about 45 seconds. My tuner was set on the SCT canned "performance tune." No I don't have any gauges before any one asks. And yes I know it was not very smart. Any ideas???