So I am getting new gears. Was going to go with 5.13. I have a Dana 30 up front with sleeves, gussets, rcv shafts and locked on 37's. My install shop does not want to do 5.13 cause he says they will break going through a ditch. I have a buddy who hasn't had a problem on his. How many have broke the 5.13's and will 4.88 even be enough of a difference to change. 6 speed 2 door. Has 3.73 right now

The lower the gears (the higher the numbers) the weaker they become. The D30 has a tiny R&P already. I would never put any lower gears in a D30 with 37's. I would suggest a new axle housing first.

My 09 had a 3.8, I was running 4:88's and running Toyo 37x13.50x17. Those are the heaviest 37's they make and it was fine in the North East.

I blew up my D44 with 4.88 gears and 37s. The RCV shafts may have been the mistake - they don't break.

5.13 gears in a D30 running 37s with RCV shafts, is pretty much a guaranteed R&P failure, unless you don't wheel at all. The high numerically the gears, the larger the teeth. The result is that there are less teeth in contact with the pinion at any given time. That is why they get increasingly weaker.

4.88 or 5.13, I would ditch the axle shafts and get some stock shafts in there.

Someone will chime in and say they've done it without issue, but reality is that a R&P failure will likely be in your future. I am in the camp that wheeling 37s and running tall gears should be done with a D60. If you don't wheel hard, then a D44 works, but everything else is still weak.

Toyos aren't the heaviest mine are heavier :( true double bead lock (trialworthy fab) with military 37's

Holy crap, hahaha. Doubt you'd make it out of the gear shop parking lot with 5.13s. I wouldn't even run that setup on a D44. Wheels and tires are just too heavy for all components.

You have more flexibility with a stick. So, 4.88 is a good option. That said, it's still a 3.8 so no matter what you do from a gear perspective, the engine still needs help.

Got a roctrac to go in it also

I agree that the 4.88 will be less likely to break,,, as far as gearing goes, they will make a huge difference over your 3.73.

That just increases the torque on the gears. Snappy, snappy :)

If you do it though, you should fan a little bracket up for the diff that holds a pin. Then when it grenades, you can take a pic of it with the pin pulled :)