Wondering if torque converter isn't locking up

Yup.  If they do come to an agreement before Tuesday then they will fight over the debt ceiling which has a deadline of the 17th.  If they get past that, whatever they agree on this week will expire in mid-November and they'll be right back at it.  Again.  I think it is highly likely we'll get a shutdown at least once with so many opportunities.

Thanks.  Nothing seems unusual during daily driving.  I think the tranny temps are slightly higher than before once it gets to max temp, but that takes so long I don't always hit that point on my 35-45 minute drive to/from work.  So hard to say for sure.  I don't feel any odd vibrations, and I'm one of those types that is always in-tune with whatever I'm driving so I'd feel it if it was there.

You say the lockup is disabled in tow-haul mode, but from what I've read the opposite is true on this six-speed, with possible more aggressive lockup in tow-haul.  I'm sold on getting the gauge I mentioned - it has so much other useful info and is designed to be permanently mounted on the dash like old-style aftermarket analog gauges so it will be permanently used.  That will at least confirm if I'm getting lockup at all in normal and tow modes.

Confirmed lockup or not, it sounds like a professional checkup is in my future... once I find out if I'm furloughed as of Tuesday... or maybe on the 17th... or maybe again in mid-November. 

No problem, question away.  It has the RPO code for the "heavy duty trailering/cooling package" which I believe includes a secondary cooler along with the one inside the radiator.  There is definitely something in front of the radiator but I've never traced the lines to see if that is it or if it's just the A/C condenser.

During this summer's trip after about 30 minutes on the road both of the temps would rise above normal.  The coolant is normally 210 but would slowly rise to 235, then you could tell the fans kicked on because it would quickly drop to 210.  Repeat the rest of the day.  The tranny temps got up to 241 at one point but usually stayed below 235 after I started using tow/haul mode.  The temp would range between 225 and 235 most of the time.  No change to my coolant temps when not towing.

I assume the tranny oil is factory fresh from 2010.  I've had it since spring 2012, about 27000 miles then and about 52000 now so no reason it would have been changed before I got it.  Checking the fluid for color and smell is part of my buying routine, and I keep an eye (and nose) on it on a regular basis.  Doesn't look dark or smell like burned popcorn even after this summer's bake-off.

As mentioned I did use tow/haul most of the time, it definitely locks out 6th.  It also adjusts the shift points and holds it in a lower gear longer before upshifting.  From what I've read it may make the torque lockup more aggressive but I haven't verified that yet.