Chrysler 8.25 upgrade questions
 

So I am running 35s on my 8.25 with 4.56 gears and 27 spline axles and I am wanting to upgrade to 29 spline but I wanna know if I should buy the OEM ones or just go with the alloy ones and which ones are better.

A lot would come down to what you do with it how hard you drive it.
If you have 27 spline and have not broken axles yet then go with stock or any after market I like Yukon but there are many out there! You will also need to change spider gears and axle bearings and seals and other related parts.

You'll have to change to a 29 spline carrier.

I already have the carrier.

Yes I was reading about it and there is more than just putting new axles.

I have been searching online and found several options in alloy, so I would like to know whether it is worth it to spend a little more cash on alloy or if the stock work just as good as I have also seen some used axles on ebay. Id also be putting in an air locker, but I am still saving some money to do that.

The shafts are not cromoly, they are alloy (like you said) so they are only 15% or so stronger than stock (of same spline count). Unfortunately you can't get chromoly for the 8.25.

You wouldn't want chromoly in the rear anyway as its major strength advantage is at the ears for the u-joints, which rears don't have anyway -- plus it can't take the heat of riding on a bearing or bending forces, which is why rears are 1541H.

Get TenFactory over AlloyUSA. They're way cheaper (around $100 per shaft) and the guy that founded them used to work for Alloy but kept all of his original materials suppliers, so it's pretty much the exact same part. Most people say a factory 29 is strong enough for 35s and a locker, but the extra strength may be worth the peace of mind (as well as keeping the factory ones as spares to limp home assuredly with).

I stand corrected.
I thought since the axle shaft acted as the inner race for the wheel bearing you had to use a softer alloy. Would be interested in seeing the longevity of those shafts.

Yea aftermarket shafts for a 8.25 aren't worth it unless you can get them used for cheap. Run stock 29 spline shafts and be happy.

This is wholly, and completely...inaccurate.

4340 rears or even 300M work fantastic.

However, in your case, I'd just buy a 29 spine 8.25 and go from there.