The Super 35 kits simply upgrade the Dana 35 to heavier axle shafts with higher spline counts and different bearings. The axle remains as a semi-floater, so the vehicle weight is still carried by the axle shafts.
The full-floater kits keep the axle shaft diameter the same, but upgrade to high-strength shafts and shift the weight off the axle shafts to the new spindles instead. Since the shafts are smaller than the Super 35 kit but are probably the same material, they are probably weaker in torsion but then they do not support the shear and bending loads from the wheels either.
i would not recommend the super 35 kit to anybody....ive had a few buddies in my day bust several shafts....the bottom line is that you are still using the weak dana 35 shafts, the ring and pinion is weak and small.....you best bet is to find a 44 or 8.8. an 8.8 is a great choice bc instead of spending 900 on a 35 kit...spend 1300 or 1400 on a stronger axle unit. they have stronger ring gear, much bigger shafts and are a better unit overall....speaking of 8.8's....i have one for sale right now if you want to upgrade.
Thanks everybody, i found on warns website it says in big letters. NOT RECOMENDED FOR TIRES OVER 31 INCHES. so i def wont be buying that. Yes i also know that the best bet is a 44 or 8.8, but I CANT FIND ONE.
Here is a pic of a stock D35 and a Super 35 shaft. The super 35 shaft does not use the same shaft as the normal d35 and there has been few warranty claims for shaft breakage. The super 35 shaft is 1.31 30 spline which is the same size as a d44. I got mine for $400 used and installed it myself. I would never pay retail for a new one. That money is better spent on an upgraded axle.
I was thinking about doing the same thing and talked to the guys at warn. They have disontinued production of the F/F axle, so parts will only be readily available for the next 5 years, however superior has started making one now.
Go with the 8.8......it will be cheaper in the long run. With the leaf sprung YJ...the swap is easy. 31 spline shafts and factory disk. Even with the upgraded shafts in the 35...the tubes are still then.
I run a super 35 kit with my 33" TSL's. I have never had a single problem with the axles. It works real well I think. If you never plan on going over a 33" tire it should work fine. Anything much larger then a 33" tire and they void your warranty. that could explain the low broken axle count covered under the warranty. I know this because my detroit locker that came with it stopped working and they replaced it under warranty. They did however ask me what size tires I had on my Jeep before they would warranty it.
Now as far as cost goes I would suggest going ahead and doing a swap. There is only a small difference in cost and usually the swap is a little cheaper. It all depends on how much you can get a 8.8 or D 44 donor axle for. With a swap you would in my opinion, after running a super 35 kit, get more for your money.