I replaced the front brakes, rotors and calipers. Yet when I put it into reverse or drive, the drivetrain (wheels) are completely locked up. I'm dragging the rear tires. I have no idea, unless the 4wd is engaged. But it doesn't seem to be.
What year TJ? Rotors changed dimensions in mid-99. Mixing pre mid-99 rotors or calipers with post mid-99 rotors or calipers will absolutely cause the front brakes to lock up.
I would completely flush the brake system. Old contaminated fluid has probably made its way to the rear and is now interfering with the cylinders or the calipers
There cold also be an air pocket in the line. I just replaced rear brake lines on a car and we had several air pockets during the bleeding process that caused us issues.