Keep in mind that the OP had a "new" transmission in the "new" truck and that's what failed. So a reman isn't as bad as it sounds and a new one isn't as good as it sounds.
And I know that the "talk to my lawyer" phrase always sounds tough, but have you read what the warranty actually says? Does it say that repairs will be made only with new OEM parts, or does it mention they may replace certain components with remanufactured ones?
Don't get me wrong, I'd be upset if I had a very expensive new truck, then something major failed, and it was replaced with a reman.