That is great news that you are giving the SX8 A try I am sure you will like it I would say the normal parts that you carry for any kit is a good starting point.
Shock shafts
plastic parts
diff gears
spur gear
I can tell you if the car is well taken care of it is very durable,All cars break but that should cover most parts.
The Truggy will be out after the new year but all is complete with the kit,we are just finishing the packaging.As far as the gears we have found that if you follow the Manuel recommend spacing you will be fine.
It is going to be a great year for TQ