axles

I have a friend who has started a modest Sprite Vintage Racing effort and 
asked the following question:

"'direct me to an explanation of how to tell superior Spridget rear axles 
from the early, inferior sort. I hope so, since I broke one at the most 
recent vintage races and have a lead on a couple of used axles."" 

Any tips that I can pass along?


Thanks,

Jim Werner
Louisville, KY
jamesfwerner.com
bluegrassclub.com   
britishsportscarclub.com