I'm planning on making the trip to Northridge next month to have either 5.13's or 5.38's installed w/overhaul kits.

Currently I'm running 35x12.5R17's and will upgrade to 37's in the future. I have the stock xfer case and JE Reel 1310's with no anti-vibration equipment.
I drive 25% off-road (mud and wet trails) 40% hwy and 35% street. The highway speeds in Oregon are a relatively low 55mph. I do get driveshaft vibes when I hit ~65-70mph but they are not bad enough for a lot of concern.

My sig has more details on my exact set-up if any of that is unclear.

What would you recommend between the two options?

 

depends, are you looking for a boost in power or just trying to get your performance back to stock once you're on 37's. if you're looking for more power, 5.38's is the way to go. if you want stock performance and better mpg, 5.13's would be the better match.

 

Power is my primary goal. I'd like the Jeep to feel as torque-y all the time as it does in 4-lo. (I do realize this is probably impossible, but I can dream)

Besides shredding a driveshaft joint or grenading the xfer case what are my possible downsides w/5.38's? The rubi D44's are completely stock besides the diff covers which I assume bears no importance to gearing.

 

Yep, it comes down to your preference for a slight bias towards the road (5.13s) vs off road (5.38s).

If you don't drive above 55 MPH and you wheel that much, the 5.38s might be a good fit for you. The difference is too obvious on the road until you reach 70+ MPH.

BTW, I would investigate the driveshaft vibrations at 65 MPH.

 

actually, your biggest concern would be the pinion blowing as it is really small in a d44. if you hammer on the skinny pedal on the rocks, you'll more than likely see this go well before a u-joint or t-case.

 

Any way to remedy the pinion issue w/out switching up to a D60?

When I'm up @ Northridge I'll ask about the driveshaft vibes.

 

yeah, stick with a 5.13

 

Well this was a fairly uncomplicated and helpful thread.

I tend to hammer on the gas, rock crawling isn't as common as mud slinging out here but there is a lot of built up tension when you go from water to heavy mud and you're moving at a decent clip. If I move to Colorado for school I'll re-evaluate my D60 position (and so will my wallet, and probably the girlfriend)

 

LOL!! well, for whatever it's worth, you "might" be okay with the 5.38's. i thought i would be but then blew out my rear end in no time at all. granted, i was running 40's at the time but then, i'm not heavy on the gas.