I have an 02 2wd scab with a 4.6, troyer tuner, intake & exhaust. It is also lifted 5" and running 34" tall nitto terra grapplers and stock 3.55LS 8.8" rearend. The truck runs pretty good with the mods but I am sure it would do MUCH better if it was geared properly. From all the gearing calculators and it looks like 4.10's would get me almost dead on to the original 3.55 gear ratio. My current diff is a 3.55 LS and the limited slip is no longer working, this is not ok as I do use the truck offroad and actually got stuck last weekend purely because my LS isnt working correctly anymore. Also I do use the truck to tow, so I am looking for more low end torque that its lacking right now, however I dont want to get too aggressive as I do road trips on the highway and dont want it revving too high for long distances. The last kicker is that I have future plans to build this truck into a long travel prerunner desert truck that will be driven pretty good in the dirt, as well as hopefully a 5.4L / 4R100 swap out of a wrecked f150/expedition and would like to not have to do this again?

Bottom line, do I rebuild my current 8.8 limited slip, and obviously go with a more aggressive gear ratio OR do I find a 9.75 either already modded or a stock one and redo it myself. Money is always a factory but I dont want to do it again! Sorry for the long thread!

 

4.10 would be about right but a 4.30 would only add 100 rpms and 4.56 would add 200rpms