Getting ready to upgrade the front end. Let's just start from the premise that I do not have enough $ lying around to swap the Dana 30 for a 44, so looking to upgrade the stock 30.

I am rolling 35's greared at 4.56 on the otherwise stock front end Dana 30, spend most of the time on trails, but do some crawling now and then. I am definitely a creeper, not a gunner.

Will be adding a truss and c-gussets as well as a locker (still up in the air over selectable vs. detroit (probably really a Yukon Grizzly)), so here is the question - when I pick a locker, do I go 27 spline because the axles are relatively easy to pull from a Junk Yard when they snap, or do I go 30 spline which are WAY more expensive, but less likely to snap?

I can see the logic both ways.

I really am interested in what you have experienced, seen, etc.

 

27 spline. No reason to have 30 spline shafts in a 30. That is way too much money, IMO.

I am running 35's, a lunchbox locker, Yukon 4.56's, and Ten Factory Chromo's. No issues.

 

There's a couple reasons I would go with 27:

1) 30 spline chromoly shafts are plenty strong but with a locker that pinion would probably become the weakest link.

2) if you did snap a shaft, finding a 30 spline replacement is a bit of a challenge (especially on the trail)

 

x2 on the posts above but I would just like to reiterate; D30's should only ever be 27 spline. I can't think of a single good reason why money should be spent on bumping up to 30spl

 

I run 4:88s/35s on a D30 Nitro 27 spline chromos... no issue yet.

However, I've contemplated going 30 spline on my next project. Your unit bearing is 27 spline... so not only are you running an uncommon shaft but now you're into "weird unit bearings you can't get off the shelf" as a friend of mine pointed out.

 

???? I'm confused on your post. The 30 spline is on the end of the axle shaft that goes into the diff, the splines that go into a unit bearing are the same.

 

They have 30 spline BIG BEARING upgrades. You can get the shafts both ways. with only inners being 30 spline, or Grande 30 upgrade that is 30 spline from diff to bearing with new bearings included.

 

I'm running 30 4340 spline shafts, and mine cost the same as the 27 spline 4340 shafts.
I stayed with the 27 spline outer shafts, so there would be a chance of the u joint or
outer breaking before the ring or pinion.

 

I have 27's with 4.56 gear and lockers in a stock D30 without truss's and a 33x12:50 tire.