Pretty easy to change the engine and box at the same time with a hoist as the entire front end comes off (Bumper, headlights, slam panel, radiator, crossmemeber etc) which allows you to pull it all out from the front and slide the replacement one in. Disconnect driveshafts, all the pipes, cables and wiring and your good to go. There are 2 different types of 8v engine (AGG & ADY)but if they are both late models they will likely both be an AGG engine code. I would say if your doing it on the ground it will be easier to just remove the whole lot rather than just the gearbox as its a bit of a faff.