if it is possible what also do i need to change beside the gearbox?? and is it an operation that takes a lot of time and effort or is it just an easy swap and replace??

alot of time and effort and would cost more than just buying a auto

Its usually the other way round.... Youll need more than the box:

• Brakes to match
• ECU and gearbag ECU
• Driveshafts
• new flywheel
• springs and shocks
• new master cylinder
• new linkage for selector
• new speedo
• additional piping
• several blanking plates for pedals, previous linkage etc
• new accelerator pedal (for kickdown)

and I know ive left something out. But to sum it up its just not worth it