???
On a recent trip to the high Sierras, I warmed up the truck to return home with our 9,000 lb+ trailer, descending from about 7500 feet. It was all coasting downhill and after about 10 minutes (running real cool) we got a real strong burning smell. Popped the hood (worried about tranny) and found lotsa smoke from something burning below exhaust manifold. No signs of any leaks anywhere, tranny shifting fine, just had to wait out the burning. Took an hour to air out cab, tranny fluid looks good and no sign of any sort of problem anywhere!!??
Anybody experienced anything like this?

 

Well your sig does not say if it is 4wd but if so the front axle vent is in the area and may have blown some lube out. This happens quite a bit, and it would be a stink

 

2 wheel drive, I even wondered if some plastic bag or something blew up and got stuck, nothing there, besides, the smell was really a petroleum type smell....