I got sorted yesterday folks. Thanks for all the help. I jammed a bolt on one of the pinion gears to the casing and spun the nut off with an air gun. Was very simple. Have the diff in my car and it is working 100% I will post up a wee pic of the long socket I made
It's just a 3/4 drive socket cut and extended with a bit of piping I couldn't get my hands on a 12 sided long socket