I believe you can order the allen socket from Performance Products in Ca. There is always Snap On is you don't mind the price, but both probably are not going to help you this weekend.
I am trying to remember when I replaced the rear bearings on my 87 16V. If I recall correctly, the axle nut had never been removed and was a mother to get off even with my 250 ft lb air wrench. Took a several blasts before it finally came loose. That is only the begining.....
What end failed??? If it is the inboard side that attaches to the diff, TRY, TRy, TRY TRY to just remove that end of the axle and see if you can remove just the C.V. joint. Might just be a circlip that holds it on the axle.(?) and you can simply replace that end.
I might be wrong, but if I remember correctly and can explain, the rear bearing has two races pressed together in the center and either the flange holds both together or one end and the axle hold the other. There is a possibility that if you press out the stub alxe, one half of the race will come with it and you will have to buy an $80 bearing. I might be wrong!!!!!
Let us know what you find. How much was the axle?