For those looking for a good quality gantry crane at a reasonable cost, I have found this item at a company called Radum in Australia.
It is a 1.5 ton gantry crane which I think would cover most lifting jobs that we would require.
http://radum.com.au/catalog/product_...oducts_id=6473
Just an update - The gantry is height adjustable from 2.4m to 3.6m.
They also have an item that you may be able to use when you plan on moving those heavy differentials around the workshop.
http://radum.com.au/catalog/product_...oducts_id=9001