Mike F
The part# for the lightweight (blue) diff joint set is 53248. This is both pieces that go on either end of the axle. It comes with the necessary grub screws and a hex wrench. You might buy a couple of them since they bend fairly easily. I prefer the standard ones. The Cross ones also fit and they are a little beefier than the Tamiya ones. An interesting note, there is an asterisk note that says "lightly grease threads when tighening aluminum nuts" on the package for the lightweight set.
You should be able to order all of the above from MDI
www.mdiracing.com I don't have a part# of the Ride tires, but I use their "type A soft" compound, grooved tires. I'm pretty sure Les at MDI can special order them for you too. Drop him an email.
I mostly run on prepared asphalt, so I tend to run the car fairly soft. I have an easier time dealing with oversteer than understeer, so I deliberately run soft so the car isn't understeering so much by the end of the day.