3.91:1 Posi for trade

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jerrygriffin

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I just bought a Dart with a brand new 8 3/4 3.91:1 ratio, and it is way too low for me. Sure would like to trade for a 3.23 or so, posi preferred. Minneapolis.
 
What kind of case do you have? I have some 3.23 gears. The gears are in great shape but are used. They are not installed in a rear, just the gears. I have a few different types of 3.23's, just let me know if you have a 741, 742, or a 489 case. I live in St. Cloud, MN, not too far away. I could use 3.91 gears, Keith. :thumbup:
 
Sorry, don't mean to hi-jack this thread but how do you tell what case you have. I have an 8 3/4 and want to find a posi pot for it but haven't got a clue what case I have :scratch:
 
Check this for ID.
Carrier Identification

The 8 3/4" rear-end is a frequent source of confusion, and the Sure-grip, as installed in the various carriers. The 8 3/4" carrier was introduced way back in 1957 and was produced until 1974. There are three (3) basic types of ring and pinions that fit these carriers. The common identifier among Mopar addicts is the last three digits of the casting number on the center of the carrier on the left hand (or driver's side). You will see 741, 742, or 489 as the last three digit;. Note: there is also #657 used up until 1964, but it is rarely found. The digits identify the pinion size and configuration.

741 1 3/8 small stem diameter
742 1 3/4 large stem diameter
489 1 7/8 tapered stem pinion.
 
Right below the pinon yoke on the left side, there is a flat area, it will have a number cast into it. The last 3 numbers will determine the case you have. Numbers will be either 741, 742, and 489. 741 (smaller pinion) is common on a-body cars. 742 is from 57-68 cars. 489 is from 69-74 cars. The last 2 are common in big cars and hipo cars (larger pinion). 742 and 489 have a great selection of gear sets. The 741 is from lighter cars and is harder to find a good selection of gears. But be sure to check your case before you get gears because it could have been swapped out with a different year case!
 
Rob...there's a casting number on the nose of the case,below the pinion on the side. It will be 2070741,or 2070742,or 2841489. If its a real early case,it could be a 18xxxxx number too,but their getting pretty old,like from early 60's.

images.jpg
 
Hey Keith I'm looking for a set of 3.23s for a 489 got any?

66340SEDAN said:
What kind of case do you have? I have some 3.23 gears. The gears are in great shape but are used. They are not installed in a rear, just the gears. I have a few different types of 3.23's, just let me know if you have a 741, 742, or a 489 case. I live in St. Cloud, MN, not too far away. I could use 3.91 gears, Keith. :thumbup:
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Thanks guys, it's in a 70 Duster, sounds like it may be the 489, I'll crawl under one of these days and check. Glad I read this, my luck I would have found a posi pot, been happy as a clam, paid a small fortune and it would turn out to be the wrong one. :cussing:
 
Rob said:
Thanks guys, it's in a 70 Duster, sounds like it may be the 489, I'll crawl under one of these days and check. Glad I read this, my luck I would have found a posi pot, been happy as a clam, paid a small fortune and it would turn out to be the wrong one. :cussing:
Click to expand...

Saved again Rob.....we don't want you doing this down the road buddy :cussing:
 
Rob said:
Sorry, don't mean to hi-jack this thread but how do you tell what case you have. I have an 8 3/4 and want to find a posi pot for it but haven't got a clue what case I have :scratch:
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A suregrip (posi) unit is the same for all three cases, there are different styles of units but they all interchange. It is the ring and pinion and hardware that is different.

On the same side of the case as the casting numbers the guys are listing is a large (1-1/2") letter or number cast in;

741 = "X"
742 = "2"
489 = "9"


Chuck
 
Rob said:
Thanks guys, it's in a 70 Duster, sounds like it may be the 489, I'll crawl under one of these days and check. Glad I read this, my luck I would have found a posi pot, been happy as a clam, paid a small fortune and it would turn out to be the wrong one. :cussing:
Click to expand...

For example.....here's mine Anyone know how to read the date code??

bh168.JPG
 
So the housings (or case) are all the same, you just want to find one a 489 or 742 pot right? As they are the stronger ones.
 
I have a 489 case with a 3.23 completely assembled. Very quite and in good shape, but non posi and would trade..
 
Rob, I call the case the part that bolts into the axle housing and all three are different. I call the surgrip (posi) the carrier and this will fit in any case. You can take a carrier from a 741 housing and put it in a 742 or 489 housing and visa versa.

Chuck
 
Suregrip391 said:
For example.....here's mine Anyone know how to read the date code??
Click to expand...

That is the first 742 case that I have seen that did not have the big "2" cast in it. It just goes to show that something is always different with these cars.


Chuck
 
The center section bolts up to the housing the same, sure grip units are the same. Example: if you have a 742 case, you can run only 742 gears. If you have a 741 case, you can run only 741 gears. The spline for the yoke is also different on some, some are coarse spline, some are fine spline (teeth). Also the u-joint size may be different too. When you order new gears you need to know what case you are going to use.
 
My understanding is though the posi ('68 down) has clutches that can be replaced and the suregrip is more of a throw away model...I think...Isthis right?
 
Jerry, Send me an E-mail robule1 at yahoo dot com

I have a 3.23 sure grip pumpkin that I may trade for a 3.91. May have a 3.55 as well. If you have any pictures of the case, sure grip and gears please send those.

Thanks

Rob
 
The 1968-1957 can be rebuilt with clutches. The 1969-1974 can also be rebuilt but they need to be turned on a lathe to resurface them. A little more work but it can be done!
 
This 3.91 I have is a 489 housing. All new gears and sure grip stuff. Would like to sell it. Any interest?
 
djwhog said:
I have a 489 case with a 3.23 completely assembled. Very quite and in good shape, but non posi and would trade..
Click to expand...


I think my 3.91 would be worth quite a bit more than the one legged 3.23 so what kind of trade would you have in mind? Where are you located?
Thanks,
 
jerrygriffin said:
I just bought a Dart with a brand new 8 3/4 3.91:1 ratio, and it is way too low for me. Sure would like to trade for a 3.23 or so, posi preferred. Minneapolis.
Click to expand...

Jerry:

I have a 3.23 489 case complete willing to work on a trade - In WI and could make the run to meet you somewhere. I am sending a PM with contact info. Thanks-

Dana
Rice Lake
 
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