Originally Posted by latentspeed

It is. You get quieter smoother universal driveshafts, quieter smoother ring and pinion, then there's shock cap and springs. I'm tired of saying it but steering is far better. Don't know if the wide rear hinge pin brace improves handling, but the screw that secures it now uses 2.5 driver, which eases the mind because the 2.0 screw looks as if it will strip out after going through the gearbox a few times.
The wide pivot combined with the hubs and shock location really settles the rear of the car down, much more forgiving.
I see no use for the new spindle carriers. The ball bearings there only add weight and bearings can't be cleaned out from dust. The .3 is easy to clean that area and I bet the bearings don't improve performance on the. 4
There are geometry differences with the new spindles and carriers that we feel gives the steering a more direct feel, and the car steers from the front now. The front is also easier to assemble and work on now, and the bearings really help keep tight tolerances.
Bottom line, there are updates that make the .4 worth getting. If you were to get the .3 and upgrade it to the .4 you'd be spending more money then just getting the. 4. Pay $5 for the super saver club at tower and you get several coupon codes, one if the codes gives you $75 off if you spend at least $499.

I wish I waited for the .4 instead of getting the .3 for $360. Right now .4 is $550+$5 supersaver membership-$75 off and you pay $480. Last month I think there was $90 off.

If you go with the .3 just get the updated ackerman plate, bellcrank steering and two 3x10 button head screws. Should be good enough. Maybe even as good.