8.75 rear end with 440 4 speed?

[dvw]

Ah, but gear ratio multiplies torque. So down the line torque load is increased. As a side note my Wife's Challenger has the stock 23 spline (rebuilt) and original 110,000 mile 3.55 8 3/4. It has never been rebuilt. Car has been 12.50's on slicks. It did twist the axle splines some.
Doug

 

[70chall440]

As indicated here, a 8 3/4 will perform well on the street and probably decently on the stripe unless you are running good slicks on a sticky track and launching at 4K+. This argument has been around for as long as the cars have been, same thing with the 18 spline v the 23 spline; lots of people parroting urban legend that a 8 3/4 will not live behind decent HP and/or a stick car and a 23 spline trans will not survive moderate HP. Well, there are lots of people who have grenaded Dana's as well as 18 spline trans; its physics, with enough power, sticky track and slicks, something has to give (traction or parts).

I've run 8 3/4's on the street for many years as have many here. Sure a Dana is more HD and looks cooler but if you are not an avid bracket racer or wanna be pro stock guy you will probably be fine.

 

[Cranky]

Everybody is concerned with the rear end, Dana 60 vs Mopar 8 3/4" but the SMALLEST diameter component in the 4 speed drive train is.....the input shaft to the transmission....albeit the 18 spline shaft or the 23 spline shaft. During a "side step the clutch" or a bonsai start, this shaft is subjected to the full torque produced by the engine at, say a 5000 RPM start, with the transmission shaft at ZERO rpm, neglecting 10% (or less) clutch slippage, this shaft will twist several degrees. After several impact twists, it will likely fail, probably right behind the clutch splines at the spline's root diameter (smallest x section). I'd be more worried about the transmission rather than the rear end setup. Just my opinion of course.
BOB RENTON

Shock loading is the biggest killer of parts. If you're racing, you can use a line lock and then give the drive train a tiny bit of clutch to take up the slack. A buddy and I ran a stick car many years back and was launching at 6k. The 8 3/4 did fine with the 3000+ lbs 69 road runner until it got into the low 11's. We killed 3 before the Dana went in and that took care of that. Shaved the ring gear all 3 times. Fast forward a bit.....took out more weight and added more power and got it into the 10.70 range. IIRC, got a best of 10.65 with it and never killed a 4 speed.