Brock, I found many sites but they all had a shortened version. Then I found a site that may explain why:
Though there were so many microphones at the game, only four sentences of the speech survived on tape. Much of the speech was lost and the following was pieced together from the various newspapers of the day:
Here's the site...they do have audio and it seems to include at lease one sentence that I could not find on others.
http://www.maniacworld.com/Lou_Gehrig.htm
Hope this helps.
Mike