Only time i've ever seen it is on home rails. West Nebraska and Wyoming. So I can't give you any hints on where to watch it from in Texas. But you should think about chasing it West to Cheyenne from Omaha sometime, pretty impressive and makes for a fun trip. Pacing it through small towns along the UP is great too as there are a ton of grade crossings.
Yep, the UP 844 and 3985 are what i've sort of grown up seeing. I remember one night, I was so excited to go chase it the next day, I was up through the whole night in my room looking at books on UP steam and stuff all the way until my dad came in at 5:00 in the morning to wake me up! I think I must have been 7 or so. They used to come to Omaha more than 3 times a year in the 90's. Had 3985 stall right in front of my dad and I leaving Omaha one time.
Some good experiences.
But I have now fallen for the Narrow Gauge. Just as David P. Morgan said, "The narrow gauge gets in the blood and will not out"!
Kevin M. Bush