I have seen absolutely ZERO reports of any actual catastrophic mechanical problems with the driveshafts.
It is, as stated more than once above, a sometimes annoying NOISE issue, but never a breakage or anything like that.
The worst that I have actually heard of in terms of actual non-noise problems is that ME and ONE other owner have experienced tailshaft seal leakage as a result of driveshaft yokes that were incorrectly or incompletely finished at the factory. This rare issue is easy to check for:
With the SSR up on a hoist where you can clearly see the underside, check the end of the transmission tailshaft, and the chassis crossmember and chassis surfaces for any sign of transmission fluid (It will be obvious, not subtle). If you see none, you are fine (and I predict this is what you will likely find).
If by rare chance you got the same yoke finish problem as I did, the cure is a warranty reopair at a Chevy dealership, in which they replace the tailshaft seal, the yoke, and often the driveshaft. Even when leaking, the vehicle is drivable (my dealer sent me away for a day or 2 while he got the required parts in), provided you don't have an absolute gusher.
Mine, once corrected, has never returned in over 7000 miles or so.
Repeating, the driveshaft issues you hear about are NOISE, not mechanical problems.
Jim G