I've asked my Suzuki mechanic - he owns an LJ and multiple (Grand) Vitaras - he says there's not another one that would fit but:
He has a used one for sale
He knows a workshop that regenrates and/or manufactures parts like this. For a Polish price
He said that making a completely new, custom shaft from scratch, for one of his lifted Whatevers was a total cost of ~200 GBP.