I like my Tom's axles and spool.....one broken axle in 2700+ runs, after I did a stupid thing swapping the axles side to side during a hurried up gear change.....
www.tomsdifferentials.com
Only other choice would be the M/W setup, but those are matched splines that don't interchange with anyone else's.
Tom also offers the alloy cap kit for 12-bolts, highly recommended!!!!