8.8 swap
I used to do this swap a lot on Jeeps.... if you can find a 98 and newer explorer rear they have 31 spline axles where as several older versions have a 28 spline. With that being said.... you have the option of jumping up to Moser or Alloy USA axles shafts for extra strength.
My question is regarding the bolt pattern you plan to use? Are you going to have new patterns redrilled for the rear or do your front and rear patterns already match up?