My dad had a 8 3/4 in his duster back in the mid 90's. (440 ran 7.30's in the 1/8th has been in the 6.80's more recent years) Would break a ring and pinion every year. Finally put a Dana in it in the late 90's and hasn't broke anything in the rear since... He did build a duster for my sister in 2011 with a 360 run's 11.80's with the 8 3/4 and hasn't had a problem with it...Keep the build simple and low torque and you'll be fine. Increase torque and power, you'll find the weak link.
Please explain then how my stock capped 742 case has lived 14+ years and most of that at 3200 lbs. w/a BB 470, running low 6's in the 1/8 and 9.70`s(5 years ago)in the 1/4 w/1.3 60 fts..............