Hi. I'm about to change my rear housing.
i'm running a 318 and i'm not going over 350hp.
Got a 83/4 with a 489 and 2.76 gear in now.
Now i want to change to a 741 housing with a 3.91 gear.
Question: Will the 741 be strong enough?
Isn't the 741 the weakest?
And have the axles the same splince?

 

I think you worry too much. I'd bet this is a fairly mild 318, not an 11 second drag car.

My first Mopar "back then" was a 69 383 RR 4 speed. It had an 8 3/4, and later headers, Edelbrock, Holley 780, and I used to find EVERY excuse to jump into it. Never hurt it a bit.

 

You will break the u-joints before you will break the rearend.

 

Honestly.... I'd stay with what you have.

The 489 case has the biggest pinion gear so it's stronger..


Plus if you're going to be mostly cruising and not racing, the 2.7 gears will be perfect.