Repro trucks are available from Trickel, wheels are available from Hennings, but no one that I have found is making axles. Trickel sent me one of his last axles for a sample, he won't make any more. Odd size, .156 brass rod from McMaster-Carr works great. Picked up some brass tube the just slips over the rod to create the spacers. Flared each end of the tubes a bit. This gives solder a place to fill and hold the spacer to the axle. Ready to populate a couple of cars.
Steve