i don't understand and can't rap my head around why every one thinks the 9" is stronger than the 8 3/4 i have used both and broke both so I started researching this subject since it first come up and talked to a lot of rear end builders and the only advantage a 9" has is a huge cheap supply of parts available for it but as far as strength the 9" has a lot smaller pinion shaft but does have a third bearing support that does make it stronger than the small 8 3/4 but not as strong as the 489 with a 1 7/8 pinion shaft these do have one problem with a stock crush sleeve it keeps crushing with high horse motors and thats why you have to install a crush sleeve eliminator in them making them stronger than a 9" this is what every shop i have talked to tells me now the dana 60 that anther story it is defiantly stronger than both and i'm told way cheaper to build but for me i really like the drop out third member I know i'm rambling but i just had to say this