Of your engine is out it will take you half an hour.
If it's not out it's easier to take the engine out with the gear box.
Disconnect the cables from the starter motor, including the earth strap.
Undo the wing nut connecting the clutch cable to the gear box and the small bracket holding the clutch cable on
Disconnect the drive shafts 6mm Allen key either 6 or 8 bolts per drive shaft (don't loose the metal tabs between the bolts)
Support the gearbox (I used a Stella crate other makes are available)
Undo the linkage to the get leaver on the front of the box means snipping a securing wire and loosening it off. Move the gear lever to 2nd gear to separate them.
Undo the two mounting bolts and woohoo gear box out.