You got it man. If I was you Id upgrade to at least the GT/Glanza gearbox for peace of mind and reliablity (as long as the donor box is in good condition), it just wouldnt be logical to stick with the na box unless you couldnt afford to upgrade it which is often the case in most situations. Also try and see what other boxes there are in the same price range, you may be surprised to find something better like the one Enzo mentioned or even a 6 speed of sorts, there are options left right and centre, you just gotta find out more about them and your needs also, but another factor is are the other ones strong enough also.. Happy hunting Kev Joz