putting Disco lt77 gearbox in a 110

Hope someone can help I have a 1986 110 hi-cap with a knackered gearbox I also have a Knackered disco with an great greatbox. I have been advised that the disco gearboc will not fit my 110, Is this really the case does anyone know how I can modify the box to fit I really do not want to go out and buy a replacement if I dont have to.

Regards littleyellowenterprise