Hi all,
There are even Quranic Manuscripts where if you look closely in the site you will even see some manuscripts 4 years after the Prophet migrated to Madinah. There also survives two of the manuscripts written at the time of Uthman. Look through the site you will find them.
Peronally, I went to a Museum in Kuwait and saw some manuscripts dating 50 years after the prophet's death.
Also, something that many people choose to ignore is the oral tradition of the Quran.
What really reserved the Quran was the oral tradition of it. Today, there are more than 10 million people who can recite the whole Quran at once. I myself can recite one third of the Quran. In every established mosque there are what we call "HAFEZOON"(Memorizers). Through out Islamic history, Mosques were filled with such people. Schools were Mosques and every student there knew the Quran by heart. The Quran was and is always easy to memorize, although it may seem unbelievable but it's true. Every single Islamic city had mosques and every single mosque had "HAFEZOON". It is this tradition, along with the many written manuscripts, that prevented the alteration of the Quran. Too many people knew the Quran, it was impossible to suggest any addition or alteration for many many others will quickly discover it.
Peace