loose differential?

I had an axle out last night and when I was turning the ring gear to take the c-clip out the diff was so loose I could move it a 1/4" back and forth ( in relation to the car) I checked the bolts and they were tight. This is the first time I've messed with a rear end. Should it be this loose?:confused: My Haynes manual doesn't say anything about checking it or taking it out even. It hasn't said anything useful about anything else I've had to work on either. WASTE of $20 for sure!)