Is this a 489?

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kdtjb

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Can't remember where I got this, but I don't know what it's for. It has a thin metal tag attached to it that has a 3.23 on it.
 
3.23 would be gear ratio.
Look for other numbers. My x refrenced dont show that casting number.
 
I may be wrong but I believe that big 9 cast up on the housing there tells you that it's a 489 housing also.
 
Odd to me, all my cases have had the stamp with 741/742/489 last three digits in that stamp. Check the Dr Diff website!

This is not a good pic with the paint marks but last 3 are 742 and there is two #2 top and bottom rib so the previous post make sense.

0E8B2B56-6F9A-410F-9EF8-92D40CD5A0EE.jpeg
 
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I think that is a pre '64 case. Pre 741. I had an earlier case, guessing late 50's early 60's, and the bolt pattern was smaller than the 741,742, 489 cases and would not fit the later 8 3/4 housing.
 
I may be wrong but I believe that big 9 cast up on the housing there tells you that it's a 489 housing also.

All 8-3/4" carrier assemblies can be identified externally by the casting numbers. Additionally, the '741' commonly has a large X cast on the left side, the '742' may have a large 2 cast on the left side, and the '489' has a large 9 cast on the left side.
 
some other 8 3/4 casting numbers to ponder. I had a -657 SG casting and it fit right into an A-body rear...I found data on a weird 8.25 axle Mopar used that had a smaller carrier bolt pattern:

"From 1957 to 1964 Chrysler manufactured a front loading center section similar to an 8-3/4". Its ring gear diameter was 8-1/4". This is not related to the Spicer built 8-1/4" rearend used in Chrysler products in the Seventies. The 57-64 was more or less designated as the the six cylinder rearend whereas the 8-3/4" was designated for V-8 cars. The 57-62 8-1/4" used a case with a casting number 1828448. It appears that in 1963 and 1964 this gearset was installed in a 741 case. The 1828448 may have used a different housing flange pattern as it calls for a different housing (1045744,2070269)


Some casting numbers: All are supposed to interchange with thrust block caveat.

1-3/8" small stem pinion... (aka. '741')...
Carrier casting numbers: 1820657 (1957-1964), 2070741 (1964-1972).

1-3/4" large stem pinion... (aka. '742')...
Carrier casting numbers: 1634985 (1957-1964), 2070742 (~1961-1969).

1-7/8" tapered stem pinion... (aka. '489')...
Carrier casting numbers: 2881488, 2881489 (1969-1974)

Thrust Block Variations
There was a difference in thrust blocks prior to 1964 that make center section interchange, as well as axle interchange problematic. The thrust block, or "axle shaft thrust spacer", its the block that both left and right axles butt up against inside the center of the differential. Prior to 1964, all open differentials used a thrust block was approximately 1/8" to 1/4" thicker than units made after 1964. The Sure Grip thrust block prior to 1964, however, was indentical to all 1964 and later Sure Grips and open differentials. In 1964, the thrust block width was changed to match the Sure Grip thrust block width.

Everything You Ever Wanted To Know About The 8 3/4 Axle
 
I would like to say that I have never seen the 8 1/4 in anything newer than a 1956 Dodge/Plymouth/Chrysler. There were also 11 bolts/nuts retaining them to the housing. Kim
 
I have a 657 8 3/4 case.It is from a 58 Dodge 1/2 ton pick-up.Gear ratio is 3.58.
 
Do they have a date code any place?
Look on ring gear and sure grip parts.
When i was looking for a center section, i looked at dozens of them on ebay and the cast in ( what should be the date code) were all over the place with numbers and letters that could not work as a date.

Example assuming a letter was the month.... Some letters were too far in the alphabet even excluding "i" and "o" etc

Previous post where i i tried to make head or tail of it all:

Need help with date codes 742 - 8 3/4 center section
 
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The foundry that cast the case did not just ‘leave the 9 off’.
The number 9 fell off the mold and they continued to use it that way. The characters that make up the part number are individual numbers that are typically silver soldered to the pattern. Do a lousy job soldering them on and they fall off while in use. At the International Harvester foundry that I worked at ,long ago, when that happened it was required that the missing character be engraved into the casting as having the correct part number on the casting was a part print requirement.
 
I thought you could mix n match pumpkins between 8 3/4's??
Good to know if not.

You can as a complete unit.

But if you change components of it (the pumpkin) you may have issues. 742 cases used a Dana 4 spider center. The 489 used the Cone type center. The over all diameter of each is different. Never had an issue with 4.56 and the small pinion but when changing to 3.55 I got pinion rub on the cone center when trying to achieve gear pattern in the 742 case.
 
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