Is my tranny or differential broke? Options

[HardHead93]

The car has been leaking gear oil. I thought it was an axle seal so I took it to my local shop because they installed the original seal and would warranty it. Come to find out it is not the seal. The axle has some serious in and out play in it. When it moves out gear oil leaks out. The shop has tried 2 other brand new axles and the problem is the same. The last axle would not click and lock in. I have a helical LSD in an S54 transmission and I am running a Gen 4 3sgte tuned for 340 hp on E85. I track the car so it gets beat on pretty hard. The shop is having a hard time getting a good part number because the original part number is discontinued but superseded by another. One axle came from OReilly's and the other came from AutoZone. Is the tranny or the differential broke or am I not getting the right axle? Has anyone else had this problem?

[Box]

There're various manufacturers of custom CV axles, there used to be one that everyone here used for when they did 3S-GTE swaps but it's eluding me at the moment. That and I think the E153 swap mandates at least one custom axle. The custom axles can withstand more power without breaking if made to be so, though there's the argument that leaving the axles as the weak link can spare the gearbox and then you just have to replace axles. Generally the axles are made of a chromoly steel and/or thicker than stock, more extreme performance variants even beef up the joints and splines. Though if you're not snapping them you should be fine with stock, just need to get one that's right or maybe just a better snap ring for the one you have.