[Rog_Van]

Does anyone know how well a 74 Dodge 8 1/4 rearend with a 3.90 ratio would hold up in a 3400 lbs car with a 350hp motor .In other words is this rearend strong enough to handle this amount of power or should I look for something stronger? I'm trying to stay with a mopar rearend and 8 3/4's are hard to find.

[plysat]

There's a lot of things that will cause rear end failure,horsepower is NOT one of then.Torque is the major one,thats what gets a car moving from a stand still,rear tires can destroy a rearend ie; sticky drag slicks.Spinning any tires in loose sand or gravel onto dry pavement,doing a burn out to impress the boys at the rootbeer stand,ect,ect.
What I'm saying is your question doesn't provide enough information for an honest answer. What is the intended use, whats the torque #'s & at what rpm,how about your tires?
Here's a question you can answer for yourself,what was the most power full car the OEM used this rear in,how does it compare?
A all new 8 3/4" set~up can be had for about a grand,axles included,add your brakes and go !
Check the Mopar mags.Good Luck

[Rog_Van]

I'm putting this in a resto-rod 39 DeSoto. The torque #'s are 425 ft/lbs with a max rpm of 6,000.
The cam is ground for lots of low-end power. No drag racing, just street driven, with an occasional "get on it". As for tires I'm thinking about 25560R15's.

[PC Hotrod]

You will not have a problem as long as the chunk is in good shape. I used an 8 3/4 Sure-Grip rear in my 1969 Charger R/T SE.

The Charger has a 440 Magnum Balanced and Blueprinted putting out more than 400 hp and +500 ft/lbs of torque.

The car was street driven hard with 245/60/15 radials and hooked-up like a champ.

Make sure you can get your hands on a Sure-Grip unit, it makes all the difference in the world.