I have a stock 07 jk sport with the 3.8 6 speed. It has 3.23 I believe. I'm running 33s. Other than lift what do I need to run 35s. I heard I should upgrade the rear and sleeve the front along with regearing. Any Input?

 

OP has a 2012, thus a Pentastar and a different auto tranny (five vs four speed) than both of your 2008s.

 

What would my 2013 JKU auto, 35" tires, 3" lift RPMs be at 75 MPH if I ran 4.88 gears. I am thinking about the same upgrade. Should you go ahead and do lockers and LSD, maybe just LSD make since for me? I am not a huge offroader but I do some. Mostly I use my Jeep to get to hunting, fishing, hiking, camping, mountain biking spots.

 

There are rpm charts at 70 mph by transmission type, actual measured tire size, and differential gear ratios in the FAQ sticky thread at the top of the Modified Tech section.

https://www.jk-forum.com/forums/modi...bie-has-18617/

Here is the Pentastar chart from that thread:

 

IF you are going LSD or full locker, gear-change is definitely the time to do it. I looked into putting TrueTracs front and rear. I like the fact that they work without operator intervention and won't wear out like LSDs.

But, then I did more research into BLD which is already built into every JK. Brake Lock Differential has several advantages:
1) No need to change existing open differential carrier.
2) No clunking and bumping from auto-lockers and LSD.
3) Easier on axle shafts and dive shafts. (less chance of shock load).
4) We already have it.

LJ and TJ with no BLD versus JK with:
http://www.youtube.com/watch?v=8bQ3NUzO80Q BLD demo:
http://www.youtube.com/watch?v=oh6-ZTRSwjs

 

I can speak for BLD. Its pretty nifty stuff. But im still opting for a rear selectable locker. I though about a truetrac but lsd engagements can be rough on axles during hard wheeling. I would rather just lock them up.

I went 4.88s. No regrets. Low range in first, jeep drives itself.