The best obviously would be to look at your window sticker from when you bought the truck, but the LT packages are the different levels of options applied into ''any truck'' exept going into the LTZ packages. LT1-2-3 would be different options included in the interior mainly. You would have to do some research online to know the exaxct options per level of interior, but for an example, the LT3 should look like the LTZ interior but can not get cooled seats and a few other small options, for those you would have to go to an LTZ. But LT1 would be basic LT interior (power locks, windows, cruise, tilt steering wheel etc.) When i said ''any truck'' meaning you can buy/order a work truck package truck with LT1 upgrade. They normally consider this a LS package but in the HD series they are still considered just a WT. I may have some info wrong because i'm not a chevy dealer but that should be the jist of it.