The Union, desperately wanting to compete in the space lanes for trade needed a cheap craft that could be built quickly, cheaply and flown by inexperienced pilots got it right on the forth attempt. By taking the chassis of a Sabre, with its familiar and forgiving controls, bolting large cargo bays, fashioned from the ageing but numerous Rustclaws, Union bosses were able to mass produce a relatively cheap trader.
Handling is not a concern for this pocket size bulk trader, nor is visibility or combat ability; however, for the budding union pilot wanting to make a buck on a shoestring, the Junker is the ship to own.