Are the newer (solid) half shafts that much stronger than the Gen 3's? Was thinking about an upgrade since adding the Paxton and 355's.
Stronger than the Hollow shafts? Yes. However, the OEM shafts are only as strong as their CV cages, stub shafts, and outer CV flanges. And needless to say.... that isn't all that much stronger. Putting solid shafts into OE CV's is certainly better than nothing and will fix most issues, but if you make big power and run sticky tires, it probably won't last forever either. Getting the cages replaced helps, but they aren't easy to find. The only real solution is to just replace it all and go back to the drawing board... only problem is cost.
It can be done a few ways:
-300M Shafts w/size 21 CV flanges inner and outer and wheel hubs to match [Rated Wheels UP on slicks]
-300M Shafts w/size 15 CV flanges inner/outer, OE outer splines [Rated 1250 w/DR's]
-300M Shafts w/size 15 CV flanges inner/outer, OE outer splines, OE stub coupler [Rated 1000 w/DR's]
The first 2 options replace the stub shaft assembly with a splined flange, and can be made direct-fit onto OEM, Giken or Quaife differentials. The last option retains the stub shaft and attaches to it like an OEM axle shaft.