the CV shafts and the center gearbox outputs are PLA the wheel axles CV printed in Nylon. the 4 small bevels all printed in nylon(12 pieces)
you want the nylon where the most shock loads are located. these are the small bevels and the wheel axles. the steering linkage can also be made from nylon if you wish.
if you have to sand the shafts to fit the bearings then you are still over extruding.
now one issue with printing the axle shafts from nylon is the 4mm bolts for the wheels will not fit. you will need to predrill them to except a 4mm tap and use a 4mmx.7mm pitch tap to finish the wheel axle bolt holes. this is because the nylon will shrink compared to PLA.
printing the small bevel gears in nylon will be difficult i recommend, splitting them from the STL then turning them over 180 degrees so the wide base sits on the bed, step out about 12 of them so that you have space between them to cool and prevent over heating(melting) use a raft and a brim to help hold down the small bevels as the white glue will not be enough on the bed even with a PEI sheet on it.
.2mm resolution and you should get good results.
also because of shrink with nylon you will need to drill out the center of the small bevel gears with a drill bit. i recommend 2mm instead of attempting 1.75mm and switching to steel rod 2mm shafts to complete the diffs. they will be much stronger and run smoother.