What we have here is yet another alternative to the serious axle game. This, like all Toyota axles is built very well and is very reliable with a couple of very good things going for it.
The first thing I noticed about the Tundra 10.5" axle is the pinion. The Pinion is nearly centered, not very low like a 9", not pretty low like a D60 or 14 bolt but up out of the way which is going to do wonders for your pinion yoke, U joints, & driveshaft.
The next thing that pops up are the 36 spline spiders and that they use the 90 degree pressure angle, not the Dana traditional 60 degree angle. This makes their axles the equivalent of a roughly 37 spline Dana axle which is a pretty damned stout shaft!
Lastly I should confess that I was looking at these 2 years ago and the price was just too high. From Toyota they were $1600 bare and from wrecking yards they were $1000-1100. Over the last few months (September '13 as I write this) the Tundra 3rd members have fallen quite a bit as they started hitting the yards in numbers and today you can get one with a low miles gear set for ~$500.
Those are the benefits and I would be in the wrong to not mention the one detriment I have uncovered while putting these together. In the US the gearing options are limited with 4:88's being the lowest, however in Australia there are several lower available and I have spoken to several of the US gear guys about importing them and a couple of them are talking about doing so. In the meantime if you run an automatic you should be fine.