I dd 5.38's with 35's and an auto. Nothing has exploded yet lol

 

Looks like you are getting a lot of different responses! I have 4.88s with 35s (manual trans), and it's perfect for rock crawling. That said, it's not so great for highway driving. I think it revs too high at 70 mph, and my lower gas mileage at this speed reflects this.

 

I dunno know if I'm missing something here but did the OP ever mention if he's auto or manual?
If he's a 4dr manual I think 4.88's would be a better fit for fuel mileage and rpm's over 5.13's if he's a 4 dr auto 5.13's are great. I run a 4" lifted JKU on 35's with Yukon 5.13's and rpm's are at about 2500 which is nice and my mileage improved ever so slightly..... It sure didn't get worse.

 

He said he runs about 3500 RPM at 70 with his setup. According to the gear calc's online, there is no way, it looks more like 2450 which should do nicely.

 

Yeah, that's where you'd be in 3rd gear. His OD is either off or broken. With OD it will be at 2500 rpm.

 

The guy probably didn't do a Speedo correction and feels like he's gonna blow up bcuz he's doin 85 not 70.

 

So what would you all suggest for a JKU, 35's, automatic 3.8 and driving about 65 in 3rd on the freeway towing a trailer? 4.88 or 5.13?

 

I went with 4.88 in mine and couldn't be happier. 5.13 will also blow your mind. It is the best investment IMO.