GM U0101 and UOO73

I've got a couple of DTC's I've been chasing. The vehicle is a 2008 Tahoe Z71. The DTC's are U0101 and U0073. They both come up simultaneously, at random intervals. Sometime in a day, sometimes several days later. But always seem to show up together. There no symptoms of any kind. My interpretation (amateur guess) is the TCM and ECM are loosing their handshake. The only thing I can think of is a wire or ground issue.  It bugs me there aren't any symptoms, and feel like I'm waiting for something to catastrophically fail. I've tried to use my scan tool to capture live data while driving around, in hopes of grabbing freeze fame data. But it never happens when the tool is hooked up. My hope is that some else has run across this.

What module is setting these codes and what module(s) do they imply have a problem?
In any case, if there is no symptom and no warning lights I would be inclined to leave it alone

U0073 is TCM, U0101 is ECM. There are no warning lights since mfg specific DTC's don't typically trigger the MIL.  U0073 indicates the TCM comm is off, and U0101 indicated the ECM has lost comm with the TCM. These two coming on at he same time makes sense to me. Seems to me if this were a permanent disconnect, there would be symptoms, and the DTC's would pop up immediately after reset. But, no symptoms, no immediate DTC's. Time does pass before they reappear. To me it sounds like an intermittent disconnect... loose wire, ground, etc.

I'm wanting to head this intermittent issue off at the pass before there's a permanent comm disconnect. 

Sounds like the TCM is where you want to focus your attention on. Powers, grounds, and communication lines. See if you have 60 ohms at pins 6 and 14 at the DLC if that system uses CAN lines at those pins.