it's always a fun debate. I've heard of guys having factory freak 10bolts... my honest opinion is get AAA and beat the hell out of the 10bolt till it breaks, then upgrade. for the record all rear ends are mechanical and with that they are all prone to failure, but the failure rate of an S60 and 9in. are much less then that of a 10... for me my car is for driving, not race specific so I feel no personal need to install either of the 2 bigger ones. besides, my tires will break loose before causing less stress on the internal components limiting the potential of failure.... since each are all with in $3k +/- $500, you may as well take the skirt off and go for the S60... i'll decide more when my 10bolt breaks,, til then i'll keep pouring gear oil in till it explodes