'61 chevy rear end
 

I've replaced the drivers side bearing twice now (going for a third). It starts leaking after awhile (few months), the shaft has no groves worn in it, the housing looks good. This rear is like a 9" and the bearing has to be pressed on the shaft, also the bearing has 2 "o" ring seals around the outside to seal it against the tube. the pass. side I replaced before and it doesn't leak. Anyone have some ideas ? (could the machine shop be tweaking the seal alittle so it will leak, or am I missing something). Is there any specs on the i.d of the tube or the o.d of the shaft.
Thanks in advance.

this is the old style rear that chevy used from 55-64, they had a lot of axle bearing and seal problems, there is a replacement sealed unit that you use with o-rings and silicone but i haven't seen one in years, the axle specs would only be in an old service manual