Differential Pinion Bearing + Race - recent rock auto purchase - don't match?

MoPar~Man

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My last rock purchase I browsed through the closeout list and for a few bucks each I bought:

Differential Pinion Bearing / Race SM88010 (this is just the race)
Differential Pinion Bearing / Race WTHM89443 (this is a bearing without race)

This is for 8.75. I'm looking at them today, the bearing is large, and a little over 1 inch wide. The race is narrow, maybe 1/2 or 5/8 wide. Besides the difference in width, they don't match in diameter either. So why don't they match? What did I end up buying?
 
My last rock purchase I browsed through the closeout list and for a few bucks each I bought:

Differential Pinion Bearing / Race SM88010 (this is just the race)
Differential Pinion Bearing / Race WTHM89443 (this is a bearing without race)

This is for 8.75. I'm looking at them today, the bearing is large, and a little over 1 inch wide. The race is narrow, maybe 1/2 or 5/8 wide. Besides the difference in width, they don't match in diameter either. So why don't they match? What did I end up buying?


SM88010 is the race, or cup, for the front pinion bearing for the 8-3/4" axle with 1-7/8" pinion (2881488 and 2881489 case) or with 1-3/8" pinion (1820657 and 2070741 case). The mating bearing, or cone, is SM88048.

WTHM89443 is the bearing, or cone, for the front pinion bearing for the 8-3/4" axle with 1-3/4" pinion (1634985 and 2070742 case). The mating race, or cup, is WTHM89410.
 
SM88010 is the race, or cup, for the front pinion bearing for the 8-3/4" axle with 1-7/8" pinion (2881488 and 2881489 case) or with 1-3/8" pinion (1820657 and 2070741 case). The mating bearing, or cone, is SM88048.

WTHM89443 is the bearing, or cone, for the front pinion bearing for the 8-3/4" axle with 1-3/4" pinion (1634985 and 2070742 case). The mating race, or cup, is WTHM89410.
Ah, ok thanks.

I have the 741 case, I don't see an X stamp on it, this is a '67 Canadian Monaco that came with poly 318 and 727, so I guess the pinion is the 1 3/8 shaft, I don't know the spline count. This also has implications for the correct axle bearing P/N's ? And seals? I remember having to buy several different U-joints to get the right size.
 
Presuming that the laser-etched numbers on each of the parts matches what the part number on the boxes indicates?
 
Ah, ok thanks.

I have the 741 case, I don't see an X stamp on it, this is a '67 Canadian Monaco that came with poly 318 and 727, so I guess the pinion is the 1 3/8 shaft, I don't know the spline count. This also has implications for the correct axle bearing P/N's ? And seals? I remember having to buy several different U-joints to get the right size.

Following is some select information on part numbers and verbiage about universal joints excerpted from my old "A Chrysler 8-3/4" Rear Axle Guide". I've trimmed it for the specifics for the '741' case, although some things like the axle outer bearing and universal joints are shared by all 8-3/4" axles. Bearing numbers are Timken base numbers. Many manufacturers use the base within their own numbers. There are more brands available for all the parts than are listed here. Chrysler numbers listed were the latest superseded numbers when the guide was written.
FYI...

Gaskets and Seals for 1820657 and 2070741 case 8-3/4" axle
PositionChryslerNationalC/RFel-Pro
Axle inner seal47966988695S15460---
Axle outer seal24042168704S19000---
Axle flange, foam2070933------13800
Axle flange, shim2881314------55032
Carrier gasket1673367------RDS 65833
Pinion seal24041218515N18708---
Yoke repair sleeve---9918799187---


Bearings for 1820657 and 2070741 case 8-3/4" axle
PositionCup/Cone. Set or KitBrand, Note
Differential, side25590/25520Timken, BCA
Pinion, frontM88048/M88010Timken, BCA
Pinion, rearHM89446/HM89410Timken, BCA
Axle, outerA7BCA (65-74)
Axle, outerBR7Chicago Rawhide (C/R) (65-74)
Axle, outerSet 7Timken (65-74)
Axle mounting flange repair kitLeft # A-7-LK,
Right # A-7-RK
BCA (65-74)
Axle mounting flange repair kitLeft # A7-LK,
Right # A7-RK
Chicago Rawhide (C/R) (65-74)
Axle bearing service kit3683966Chrysler (65-74)

Universal Joints and Yokes

Universal joints for the 8-3/4" rear axle are relatively straight forward, with only two sizes/types for most applications, and a third only for certain applications. Which of the two most common sizes are types were installed in a vehicle might not always be clear, but is easy to determine from observation and measurement.

The 8-3/4" rear axle was offered with two size cross & roller style universal joint. These are referred to as the '7260' (2-1/8" yoke ID) and the '7290' (2-5/8" yoke ID). Most Imperials and some C-bodies used a different universal joint. The '1330' type joint was used on Imperials and others with a constant velocity joint. The '1330' uses outside snap rings instead of the inside snap rings used by the '7260' and '7290'. The cap diameter for the '7260' is 1.078". The cap diameter for the '7290' is 1.125". The '1330' style joint cap diameter is 1.063".

7260 and 7290 are reference numbers, but not part numbers, for the smaller and larger cross and roller universal joints commonly used in most Chrysler passenger cars and light trucks from the late 1950s into the 1990s. These were made by the Chrysler Detroit Axle Plant, as well as propeller shafts (aka drive shafts), axle shafts, rear axle assemblies, yokes, etc. The plant operated from 1917 (under Dodge Brothers until 1928) into 2010 on Eldon Avenue in Detroit, Michigan.

There are four different yokes that have been used with the 8-3/4" axle for the '7260' and '7290' style universal joints. The '741'/'742' assemblies used a coarse spline (10 splines) drive pinion. Most of the aftermarket gears also use this coarse spline yoke mount. There is a small yoke for the '7260' and a larger one for the '7290'. The '489' assembly used a fine spline (29 splines) yoke. Two additional yokes were used for the '1330' style universal joint in constant velocity applications, one for 10 splines and one for 29 splines.

NOTE: During the phase-in period of 69-71 for the '489' unit, there were several permutations of pinion size and yoke availability. 69-70 '489' units may be equipped with a coarse (10) spline pinion, particularly for the '7290'. There are two yokes for the '7260' and '7290' universal joints with fine (29) splines.


Universal Joint
(Detroit reference)
Chrysler
(OEM or DC/MP)
Precision
(Moog)
Dana
(Spicer)
TRW
(FederalMogul)
7260 joint4364400315G5-1306X20030, 20030P
7290 joint40570253165-1309X20059, 20059P
1330 joint25332023545-213X20064, 20064P
Combination ---3475-527X20226
7260 strap kitP4120468318-102-70-38X20704
7290 strap kitP4120469492-102-70-28X20705


- The combination joint is a combination of the 7260 and 7290 universal joints to allow mating of the two styles.
- The 'P' on the TRW number is the performance/heavy-duty version.
- DC/MP = Direct Connection/Mopar Performance.
 
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