T-56 Transmission Install Thread
You have to be careful about backing up the trans because of the clutch though. With the stock Viper setup (and I believe LS1), the throwout rides on the front face of the trans, and moving the trans back without moving the flywheel with it means you're putting a potentially large gap between the throwout and the clutch. You may not have enough stroke to get full disengagement if you go too far. You could shim the throwout forward to compensate though.