Howdy T444,
Parts are easy to get through the dealers, especially the 416. Your useage sounds like you would do just fine with the regular axles. Going to 12v is a hot topic. Some say why and the others say why not. It comes down to the individual. Some people who leave it 24v just get converters. In some applications it is nice to have the 24v. I will let Greg answer your questions on the machine itself. Just fyi there is a 416 in Virginia for sale. Don't know details.

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Frank X. Morris
17 Kia Niro
08 Jeep Wrangler 4 door unlimited