As far as the transmission goes Im sorry for your loss, let us know if the techs can tell you exactly what failed.
And as far as the v8 vs v6 crap goes, its all in what you want in your vehicle and what your gonna use it for. The durability on both engines is extremely good and they are both reliable. They both have their own little personalities with the little tick of the v6 and the piston slap of the v8. Neither one is the best engine designed or best engine ever built. The v8 has nice power but they require more maintenance, the engine also is forced to be AWD for 4runnners vs selectable 4x4 for the v6's.
Any and ALL engines can and will fail. Its a fact, anything mechanical will fail at some point. Thats why different metals are used so that certain parts wear out faster, thats why they are "wear" items. Different year models have different transmissions for the v6 for the 4spd vs 5spd, while the v8's always have the 5spd to try and have decent mileage.
The reason people will stick behind whatever they own is because they chose it for a specific purpose, either mileage, selectable 4x4, less long term maintenance costs, towing, blah blah blah. So thats why people are bias so if anyone is reading the thread and is thinking of what they want or should be looking for, chose for you and not because someone says one engine or model is superior to all others. You wont go wrong with either set up so lets leave the hate talk out of here-