Ok--I'M IN NEED OF HELP BOY'S--My car a 70 Duster with 8-3/4 now has 741 case with 3:91--I'm going to be upping the hp quite a bit and I'm confused with the center section and what to do--Complete street car,Maybe,Maybe once to the track to see what she'll do.I have been told the 489 case is bullet proof but what are the limiting factors on the 741??? If the 489 is the bullet proof case then why do all the aftermarket company's use the 742 case as the basis for replacement cases and center sections??? Has anyone broken a 741??? I know it's the pinion shaft and bearing that are bigger in the 489 but is that true for the 742 case also???? Do I have a concern for my 741 if I'm NEVER going to be putting slicks on it??? I guess I need to know if I should be looking at a different case and center section for security reasons?? Hp right now is 380 to the rear tire and after my motor build i should be seeing 500 hp to the wheels--Once again I need your help and thank you guy's for the teaching--Steve