Originally Posted by LilBlueTank
what exactly is a super 35 kit?
Imitators aside who sell lower quality/weaker kits also called Super 35 kits, the true Super 35 kit is made only by Superior Axle. Superior Axle neglected to copyright their Super 35 name so others have stolen it for use with their imitator kits.
Superior Axle's Super 35 kit beefs the rear Dana 35c axle up to nearly the strength of a Dana 44 which is more than strong enough for a locker. It replaces the weak OE 27 spline axle shafts with hardened alloy 30 spline axle shafts (a bigger diameter) and replaces the differential's carrier (the part that holds the gears) with a full case locker like a Detroit Locker, ARB Air Locker, with one or two others I wouldn't recommend. A Dana 35c with a Superior Axle brand Super 35 kit installed actually has slightly stronger axle shafts than a Dana 44 axle has. The Dana 35c's ring & pinion gears (which do not get replaced with a Super 35) are still not going to be as strong as those in a Dana 44 but it is the Dana 35c's axle shafts that are the most breakage prone.
While not cheap, Superior Axle's Super 35 kit is a very good way to upgrade a Dana 35c axle to make it very worthy of 35" tires and a locker.
You can always add a locker to the front Dana 30 first if the cost of a Super 35 kit is out of reach for now. The front Dana 30 can handle a locker without much issue (especially with 33" or smaller tires) with recommended lockers including the No-Slip, Aussie, and Lockright. Where a Wrangler TJ is concerned, contrary to the generic warnings against installing a front locker without also installing manual unlocking front hubs, a front locker does not (!) cause any steering or handling issues when a TJ is in 2wd.