I have always ran 742 & 489 cases & never had an issue. I have 4.10 742 now in my car & wanting to swap to 3.90 gears which I already have in a 741 case I had in a truck & they were quiet & good running but it’s in the 741 case which I’ve heard bad things about.

Car is 3090lbs & running 8” slicks with an auto,

Wouldn't scare me in the least.
Doug

I ran a 741 3.91 SG in my Valiant on spray with a brake. 3340# and went 12:00@110. It's still alive.

My 1969 Dart GTS ran 11.22 at 122 MPH foot braking a 440 with the original 741 clutch type posi with the original 3.91 gears more than once, your good

this is a timely discussion for sure.
i'm in negotiations for an engine from a member, and the package includes a 727 with a brake. i was considering changing out the valve body, because my charger [around 4k with my butt in the seat] has a 3.91/741, leaf springs, and 12.5x29 tire combo that isn't going to be changed. the converter included is a lupo 4200 or so. i figured foot braking is for me. i never used a brake, they were not invented when i got out of the "fun".
anyway, the 741 case has me wondering as well. especially as my combo is considerably heavier than the OP's setup.

The real issue with the 741 is the lack of new gear options out there. Which is not an issue for you. As to strength the 741 is very under appreciated. I wouldn’t hesitate to run it.

Should work fine for a long time. A buddy of mine had a BB Duster that he drove to work. That car went 10.90's in street trim with a 8 3/4 out back. He never had any issues with the rearend.

thanks guys ! that puts my mind at ease ! hope the OP doesn't hate me for the interruption .....

"Back in the day" when Top Fuel dragsters changed from the Olds rear end to the 8 3/4", they would go to a wrecking yard and pick up any 3.91 one-legged pumpkin they could find and most didn't know the difference in pinion sizes. Lots of 741's went in the sevens at over 200 mph with few failures. Of course the slicks back then....

I ran a 741 case 8-3/4", 3.91:1 ratio sure-grip in my #4,150 Charger that ran in the mid 12's for 10 years. No issues with the gears, but when the car started running quicker than 11.80's the limited slip started making poping noises. I never fixed the limited slip unit, and just swapped in a Strange S60, 4.10:1 gears with a spool.

My Friend ran a bunch of 10.20 at 128/129 in the 1/4 with the 741 case. But I don’t remember what gear ratio he had. The car was a low deck 470 in a 68 barracuda convertible.

max wedge cars had them and if you measure the output shaft on a 727 they are very close to the pinion shaft diameter

Moparts:

741; great rear, run it!
742; 8.75's are weak, get a Dana!

LOL

Yeah, I know, application, application, application....
But it's still funny.

It's almost like the pinion isn't the weak spot

The smaller pinion gets MORE respect!!! OMG...think about that! Is this some sort of alternative reality???

It's light weight! with less drag!!!

That's just it, it isn't smaller. They all neck down to the same spline diameter. There's a post in the tech archive that shows all the dims and as small as the 741 is perceived to be, it's still bigger than an OEM Ford 9".

Kevin