axle tube leak

[chris71]

Guys, i am pretty sure i have a leak on the passenger side of my rear diff. where the axle tube meets the central housing, not a huge leak, just a drop here and there, i will double check to make sure it isnt the fill hole leaking down and around. can this be welded to stop the leak?, i am only a beginner welder and am not sure if you can weld steel to cast iron? the only other things i can think of is A - get new housing or B - clean the joint, use some silicone or gasket maker on the outside of the joint, and go over it with a few coats of paint to help stop the leak. the rear is a 3:08 posi, that i will be taking in to get rebuilt soon, just wondering if this can be fixed or should i get a new housing. the tube does not appear to be seperating from the housing.
Thanks in advance.