5.67 Gears?
#21
JK Freak
Throw in an Atlas Rubicrawler and your problem may be solved, you get the added gear reduction when you want/need it and you get the option of doing it in 4 or 2 wheel drive. I have Pro Rock 60's with 5.38:1 gears, it's as tall (or low of gearing) as Dynatrac sells with the Pro Rocks so I would think that's all you can go for. Around town/hwy running 40"s, the 5.38's are fine, but on a few trails with steep sections, the stock trans and engine seem to be working harder than I would like them too. I'm going to do, at a minimum, the Rubicrawler addition or maybe just an Atlas T-case. If this isn't the route you like, you need to look at Ford 9" or a Corporate 14 bolt, for the taller than 5.38:1 selection. Currie Axles makes a Ford style 9" that is (I think????) compatible with the JK. The Corporate 14 bolt, well you are looking at custom builder territory there, but anything is doable.
I think it is Currie that makes the 9" for the JK which would probably be better than a D60 any ways for the weight factor. I believe about 70 lbs less for the 9". over all, most people will not see justification for the expense to run a 9", a D60 and 5.67, or the 14 bolt just so they can run 75mph or higher, but hey, it's his money, lets build him new diffs and tranny.