I suspect you may have a 1.4:1 transfer box fitted as standard. Take a look at
www.ashcroft-transmissions.co.uk for loads of accurate info.
I've got my transfer box out at the moment, but it's easy when there's no body and it can be lifted out from the top! As previously stated, it's quite heavy and the weight is not central, so be very careful dropping it out from below if you don't have the correct transmission jack cradle.
If you buy and early one, the input shaft won't be cross drilled and seems to be prone to wearing the splines. Check this before buying a used one.