She's just west of Denver right now and
apparently leaking ATF from the cooler or cooler lines. It blew back on the exhaust and started smoking.
And I had the transmission cooler lines replaced by the Chevy dealer!
Edit: well, apparently it was engine coolant leaking and not ATF. She's unloading the horses somewhere and getting it to a dealer.
Edit #2: She got somebody from the west slope to come over and get her and the trailer and the animals, and leaving the pickup at an independent shop to be be fixed. Hopefully it's just radiator or heater hoses but they say that they are hard to get to. More buck$ (hers, this time)