Thanks for the input folks, I don't have the facilities for lifting the whole car so that's not an option. I will soak the unit in WD40 and see if that frees it. I just wanted to confirm that it does come apart. My challenge is that I have a steeply sloping garage and I have just one shot at driving the car in to the garage, getting engine and box out and then sliding the car back down the hill so I can lock my garage up. If I mess it up Mr and Mrs Cock up will pay a rather painful visit to Enoch land
Thanks again for the input - Matthew, I might take you up on your kind offer if I get stuck.
All the ebst,
Enoch