4340 won't hold up to riding on a bearing in a semi-float configuration, that's why they are 1541H (which should be plenty strong enough for most applications if you have the 29 spline flavor).

 

Ok thanks Is it worth upgrading or just keeping oem shafts?

 

I upgraded only because I got a good deal on them at the time, but OEM should hold up to 35s and a locker with proper throttle control. Best part is they are cheap, plentiful, and aren't side-specific, so there's no reason to never have some spares.

 

I wouldn't waste on them personally. Rather have a spare for next to nothing.

 

Running Nitro 1541H 29 spline shafts, i don't worry about breaking and have stock as spares. Good idea if you wheel hard.