I was going to suggest the same axles as justin did. the MKIII axles are quite strong. I dont know if the inner joint is different or not, but I have heard of people installing a MKIV diff and housing into a MKIII but I dont know what they did about the axles and if the bolted up or had to change the joint or what. But if it connected fairly easly, then I would suspect that you shouldn't have any issue changing over to the MKIII axles.