over 430 per axle for pot metal (zinc) is more than i consider it to be worth.
depending on your other components you can use several aluminum axles for under 150$ each that will be just as strong.
http://store.rc4wd.com/Scale-Crawler-Axle_c_12.html
i have been trashing the trex60 in my 1:8 scale offroader. but you might look into the worminator for a truck, as it can be multi axle linked easily.
they did have a great remote lockable axle but that has since been removed due to availability. im sad i couldnt get any myself..
another option are the tamiya truck axles. those have differentials and have heard of them surviving extreme loads. rc4 are locked with no diffs unless otherwise noted. thats my only gripe with them. pretty miserable turning on pavement