are you positive they actually replaced the seals? if they did they must have fuct them up when installing the axle. the seals are kinda the same shape as a tire, imagine that instead of air in the tire there is grease. itseams like the grease should help seal in the fluid, that is if you have new seals. rust on the axle shouldn't be a problem.

dsm/mitsubishi service manuals https://www.mediafire.com/folder/5k14qlaulb9s1/dsm_mitsubishi

service manuals(my whole collection) https://www.mediafire.com/folder/ac51jwwa3g1n1/automotive_manuals