Geez , I just wanted to know how much.MOTOR- POWER- TORQUE-SNOT -an 8 1/4 rear would take....Sorry I used the wrong word ...guess I should have said torque, but I thought all you gear heads out there would get the message..Car is 3000 lbs. motor is a 493 stroker.never been dyno tested..moved a 3600 lb car with 3;55 gears. with poor tracion .. 1.67 60 ft. to 11.35 at 119.5..now that motor is going in a different car that has 8 1.4 rear..foot brake 3000 rpm stall.. just wanted an opinion on rear life.. thanks everyone for your input..

The simple answer is a 493 will kill an 8-1/4 in a short time, especially if it dead hooks, or spins then hooks.

Hope this helps, my 64 Plymouth with an almost dead stock LC 440 (509 cam) and a 3800 vert, 14-32 Firestones 4.88 gear ripped the teeth off an 8-3/4( all of them) with Strange axles and spool in 25 1/8 mile runs. I seriously doubt an 8-1/4 would've lasted that long. There are many factors in the equation, but tires, weight and RPM launch are the main ones you need to look at. Run it till it breaks (it will) then step up to the Dana and never think about it again. J

Spend all you can on a 8.25 and it will not be as strong as a stock 8.75. Break it and take the trans out also.

I agree

Don't waste your money trying to make either an 8 1/4 or 8 3/4 live. Even a stock Dana 60 will out last them and probably for less money in the long run. Break a rear end and replace your slush box.

But if you already have an 8.25 like some of us, and don't plan on racing it with tons of grip, it will last, so why spend on big bucks on the initial purchase of an 8.75 and doing the swap?

The reason I jumped all over you for saying horsepower is probably because in so many cases the "hp rating" method is used when it isn't horsepower that matters. Case in point: Connecting rods, where it's the rpm and the piston mass that cause failures not traceable to detonation. Transmissions and rear ends transmit torque and that's how they should be rated. So it's a pet peeve of mine, hence the reaction.

Now on to the question that it seems likely you wanted an answer to: Will an 8 1/4 live behind a 493? not very likely. Chrysler put the 8 3/4 behind 340s, telling me they didn't trust the 8 1/4 for that torque level.
The only stock similarities I can find is the mid '70s Cadillacs with their 500 inch motor. The 472 came out in '68 and I think they were using an 8.5 rear although it could have been an 8.2".
By 1970 they were using the GMC 8 7/8 truck differential. My conclusion is that there was enough trouble with the axles to justify a switch. Those engines had gobs of torque and a 5000lb car to accelerate.

I think you built the 493 to use, and you will press down hard on the gas pedal from time to time. It'll just take one time for the rear tires to hook solidly and the rear will be broken.

IMHO a bigblock stroker deserves a Dana 60.

R.

One other thing, you break an axle and the tire-drum might pass you going down the road, nothing to keep it under the car except your quarter panel when it breaks.

A 8.25 rear end will last for long time with up to 300 rear wheel horsepower The torque of the 493 you have will kill it in short order if running slicks or 11.5 inch drag TA's like I did but up until then I had close o 800 runs including two trans explosions that took out trans and drive shaft split in two my 8.25 survived all that and broke the spider gears Open rear end Fixed it in parking lot and drove it home