Automatic Hubs going bad again?

[cat5]

I had the automatic 4X4 hubs replaced on my 1994 Explorer Sport 3 years ago. I don't use 4X4 that much, and have never switched into 4X4 at high speed or used it on dry road. But now, 3 years later it appears that the hubs are going again.
I hear a grinding noise from one of the hubs while making a turn. Usually backing while disengaged will clear the noise for a while, but it may come back at any time.

I am taking the vehicle in for service tomorrow 1/2.
Thinking that if hubs do need to be replaced again to get the manual instead of auto.
I am told they are stronger. But do I really want the inconvenience and possible hazard of having to get out of the vehicle to engage?
It's not a good idea to do that on the shoulder of I-80 in NJ, especially when there's snow on the road.

Any thoughts on auto vs manual?

Thanks

Frank