This should dispell the 8 3/4 myth that's been around for so long......

[Cranky]

http://www.doctordiff.com/blog/tech-info/rearend-pinion-comparison/

The article starts out by saying.....All Chrysler 8 3/4″ rearends are good all-around designs, with none having a significant design advantage over the others. The 741 case 8 3/4″ has unjustly earned the reputation as a “weak” rearend, which these pictures will dispell.

Click the link and read and see what he's talking about....and me! Now all we need is an article about the cone vs clutch units lol

 

[moparmarks]

I'd take a 741 SG diff over a 489 SG any day and 742 over them all.

 

[oldbee]

Personally i'd take a 8-3/4 over any 10-12 bolt Chebby. Got a "cone" now in mine,but it is what it is.

 

[khryslerkid]

I've never known Cass to be wrong yet. He's been very helpful to me and I know a lot of others. He's an asset to our hobby

 

[moparmarks]

Just shelled out the cone clutch in my 489 3.55 SG in my 72 SSP. Just threw in a 742 3.55 SG so I'm back on the road.

 

[70B5Cuda]

I'm with Moparmarks....742 is best, then 741, and 489 is a last resort just because it's a cone style suregrip while the others are clutch.

 

[69Bee]

While I won't disagree with the article, my reasons for not wanting a 741 is the lack of gear ratio support. DD only shows 2 gear sets (3.55 and 3.73). The other two have a number of ratios available.

 

[threewood]

I have 741 cases in both my B bodies and have never felt them to be the weak point. The u joint will break well before the pinion imho. And it needs to be mentioned that the 741 was installed by the factory behind the max wedge cars.

 

[moes]

My 1970 383 RR, 4 speed, had 741 SG with 3.55 gears, I never had a problem in the ten years I had it and I drove that car like I stole it.

 

[dadsbee]

Been dumping the clutch in my 383 Bee with a 741 and highway 2.94's since 1979. On disassembly and overhaul last Fall it's like new inside! I re-bearing / sealed the axles and put it back together.

 

[moparnation74]

Good article.....but I will stay with my DANA

 

[Cranky]

I'm with Moparmarks....742 is best, then 741, and 489 is a last resort just because it's a cone style suregrip while the others are clutch.

Well, these days it could be a clutch or a cone since there's not that many out there anymore that someone hasn't been inside of. I got a cone unit from a member here and it looks like new inside not to mention what I said in another thread about keeping the cone SG's for myself and selling the clutch types because they brought more money. Truth is, I've torn down more cratered clutch SG's than ones with cones.....

 

[watermelon]

like Dadsbee above, im running an 8.75” with a 741 case however i put in a Truetrac.

i have yet to try a two wheel burnout. maybe after a few more miles.

 

[threewood]

Good article.....but I will stay with my DANA

like Dadsbee above, im running an 8.75” with a 741 case however i put in a Truetrac.

i have yet to try a two wheel burnout. maybe after a few more miles.

My little 318 poly has a TruTrac and 3.23s and it will lay 2 nice stripes when I romp it! No break-in lol.

 

[beanhead]

I always heard a 489 with a solid spacer instead of the crush sleeve was the strongest, since it already had the largest pinion stem diameter (besides the Dana of course..) but then I've never broke any of mine--lucky! The cones just aren't as rebuildable, right?

 

[furryfrog]

This article has given me more confidence about my 3.23 geared, truetrack 741 case. Lack of available gear ratios is a reason to go with a different case though as previously mentioned.

 

[john-9]

I always heard a 489 with a solid spacer instead of the crush sleeve was the strongest, since it already had the largest pinion stem diameter (besides the Dana of course..) but then I've never broke any of mine--lucky! The cones just aren't as rebuildable, right?

741 case --- 1.375 pinion stem diameter
742 case --- 1.750 pinion stem diameter
489 case --- 1.875 pinion stem diameter
Dana 60 --- 1.625 pinion stem diameter

 

[moper]

On a car that really stresses the rear itself (most don't) - the axles will twist, and the housings and perches will bend long before it shears the pinion. I'm not a fan of the cone types myself because I have had customer's cars that ate them in short order. I like True Tracs.

 

[pbiggs]

I'm with Moparmarks....742 is best, then 741, and 489 is a last resort just because it's a cone style suregrip while the others are clutch.

Does anybody know if any early (1968) 489 cases came from the factory with clutch type Sure grips instead of the cone type?

 

[Cranky]

Does anybody know if any early (1968) 489 cases came from the factory with clutch type Sure grips instead of the cone type?

Since I wasn't working on rear ends when they came out.....couldn't say but based on things that I took apart during the 70's, would have to say it's entirely possible. Started doing 3rd member swaps in the mid 70's plus most of the cars I was working on were newer than 67 and do not recall seeing a clutch type LSD unit in one....but man, that was 45 years ago lol. Didn't start building rear ends and learning about them until the mid 80's and that was well before the internet for me.