Welcome to the best explorer site on the net! You will find all the answers to your questions here.
I have the Warn hubs on my 91 and they have worked flawlessly for me. A few people have Mile Marker hubs but I have not seen them or heard much about them.
My Warn hubs cost me $150 including the conversion kit which consits of 2 nuts and a washer per each side. It took me about an hour and a half to replace them myself. I did a little modifying to mine which I included in my 1.5 hrs time.
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