Which driveshaft?
 

I am ordering all my stuff for my Wheely King, and am not sure which drive shafts I need. Is it these? http://www.rcplanet.com/Traxxas_Driv...p/tra5451x.htm
or these? http://www.rcplanet.com/Traxxas_Half...p/tra4951x.htm What else do I need besides the ST racing kit and the Shafts?

It will get:

Flat Irons
Extended Wheelbase
45T motor
Lockers

the first one listed

Hpi heavy duty gears with pede shafts and axial tranny.

If you're going to be running the stock trans and stock pinions, you could use Revo shafts (which are the first one's). They fit both the trans and axle output shafts, and are way beefy. They of course are larger in diameter though, so you'd need to have the room for them.