What options do I've left?

[deuce_roadster]

What Kube said x3.
All the other things mentioned will most likely not allow the proper torque on the nut to prevent the axle from breaking due to the drum working back and forth on the key. The key has NOTHING TO DO with driving hub of the car, it is the taper on the axle against the taper in the drum which requires the torque on the nut to be VERY tight. I am talking over 150 ft/lbs. The best way to achieve this is to tighten the nut up to say 75 lbs with a torque wrench that is good to over 200 lbs, drive around the block, keep tightening it and adding more torque to the point where after you drive around the block, it no longer is loose (you are working the drum onto the taper}. Then and only then take the torque up to around 195 ft lbs. DO NOT try to take the nut up to max torque all at once even on a NOS axle. The tapers on the axle and drum need to be clean and dry.
Improperly torqued axle nuts are the cause of the ends of the axle breaking off and the wheel and drum exiting the vehicle. This is a safety issue you cannot ignore. People new (and not so new) to the Old Ford banjo rear ends may not understand this. I personally have seen 2 cars on different tour lose a rear wheel and tire, damaging the cars and nearly causing an accident with oncoming traffic. Just be smart and safe.
ALL used axles need to be magnafluxed and checked for cracks before use, new ones are getting pretty scarce.

[ford38v8]

Originally Posted by deuce_roadster

What Kube said x3.
… tighten the nut up to say 75 lbs with a torque wrench that is good to over 200 lbs, drive around the block, keep tightening it and adding more torque to the point where after you drive around the block, it no longer is loose (you are working the drum onto the taper}. Then and only then take the torque up to around 195 ft lbs. DO NOT try to take the nut up to max torque all at once even on a NOS axle. The tapers on the axle and drum need to be clean and dry...

I respectfully disagree. Drums should be lapped to the tapers, then thoroughly cleaned, new keys installed and torqued to the full 200ft lbs. NOW is the time to take a short run around the block, to include a left turn and a right turn, and recheck the torque. Any joy ride taken without lapping or before full torque can compromise the integrity of the axle.