Trade up?

[67-Fury]

Each case has its own Ring and Pinion.

 

[BigFury]

that's been my understanding. Excellent visual aid btw lol

 

[70bigblockdodge]

You will not be able to swap gears from case to case but the suregrip will go in any case. The 741 case runs a different side/carrier bearings from a 489/742.

 

[furyus 67]

Great! Thanks again Dave! The 3.55 I have are from a 481 so it might happen! We will see how I like the 3.91's 1st.

 

[polara66hardtop]

741 is 1 3/8. 742 is 1 3/4, 489 1 7/8. The 741 is still a tough unit. My 383 dart came with it.

 

[70bigblockdodge]

Very hard to break a 741 without slicks or total car abuse, mashed gas yanked into low neutral drops, and even with slicks Axel will usually break first.

 

[Samplingman]

Since the 489 case is not a Sure-Grip, i think i would do it. What gears are in the 741?

Didn't know this. I'm pretty sure my vert has sure grip and it's a 489 case with 2.76 gears. I did not tear it apart, so I have no visual inspection, but spinning one wheel with the axel raised, they both go in the same direction. I always thought that was a good test for sure grip.

 

[70bigblockdodge]

That's usually a good indicator especially if driveshaft is attached.

 

[moper]

Look at the picture. The three pinion designs all use the same size where the yoke splines on. What that means is they all have similar strength. What differs is the bearings, and how the pinion bearings are preloaded. the 489s have the largest bearings, but use a crush sleeve to preload the pinion bearings. I convert all the 489s I do over to the shim/spacer setup to avoid the crush collar allowing the preload to change.

 

[twostick]

If you look at the pinion shaft you will notice they are all the same size at the yolk.

489 cases a lot of times came with cone type sure grips which are less preferable to the çlutch type.

Kevin

 

[commando1]

I convert all the 489s I do over to the shim/spacer setup to avoid the crush collar allowing the preload to change.

can that be done to the 9-1/4"?

 

[70bigblockdodge]

$$$$$ anything can be done.

 

[commando1]

$$$$$ anything can be done.

 

[twostick]

can that be done to the 9-1/4"?

http://www.summitracing.com/int/parts/yga-55048/overview/

Kevin

 

[70bigblockdodge]

http://www.summitracing.com/int/parts/yga-55048/overview/

Kevin

Better off contacting a rear end specialty co. like Moser, DTS, etc.