I have to agree the few 8 inchers my father and I grenaded was a result of main cap walk/crack/failure. ARP bolts help a ton also a good after market pinion support will help it live longer but they still are only good to abour400hp max automatic under 3500rpm launch with slicks. Add a manual in to the mix and 325 hp would be pushing unless you were running tires that break loose easy. I have seen a few twisted axles st the splines but never a broken one. A friend runs dutchmen axles in his so far so good after 4 seasons.... He has a stick/slicks leaves the line at about 3800 in a 67 fastback mustang. My dad ran 8 inchers behind 427 four speed in his fairlanes. He would destroy one almost every year. It was still worth a couple .10s though less friction and less weight overall....he found that out after one of the 9 let loose and he only had a spare 8 handy to get ready for a weekend race. I think the 8 does not get the respect it deserves but IMO if you are building a real race car 9 inch is the way to go for longevity.
