Jeff,
Are you not able to order from
http://www2.usfirst.org/2003comp/MMHorderform.pdf. Next day air is available but I would ship directly to your hotel in Houston. I am checking to see if we still have ours, I am not sure if we still have them since we built custom transmissions this year.
Additionally, I don't think these transmissions are meant to shift while under load. If that is what you are attempting it is possibly the reason you tore out the mounts. In between low and high the trans is in neutral and the motor is likely revving high with no load. Also, have you removed the shaft locking devices? These play havoc with the drive train when no motor drive is occurring but the robot is still moving. Glad to see you are getting a chance to come to Houston. Good luck!