2 - 3 hours
The old rear case was starting to break up, cracks have appeared around the headphone jack and in the centre of the dock connector,
The replacement went ok, wasn't as easy as I thought it would be as the replacement case had a few faults such as a screw hole for the Mute switch and a screw hole for the on/off button were filled with the glue that is used to attach the front metal bezel to the rear plastic case. Also no thread on one of the vibrator mount screws. If your not a handyman then maybe you shouldn't attempt it. Glue was removed from the holes with a red hot pin.
Be prepared to do some modifications, you need to transfer the 2 locating pins for the logic board from the old case to the new.
Make sure all the metal tabs and holes are in the right place, all must line up before tightening the screws, this includes heights and depth.