741 Housing, 742 ring and pinion..... can it be done?

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The diameter of the different seals at the yoke are all the same. The difference is which case you have. 741,489 use a NAPA 18708. While the 742 uses 18912.
 
famous bob, Yes that is correct.
the point is that even though the 489 pinion is a much bigger pinion then the 741, they all have the same diameter at the Yoke splines. Sooo, those that have snap a pinion at the Yoke, it wouldn't have matter if it was a 741,742 or 489 the material is the same thickness. IF it failed at the cap....There all the same there too........If it failed at the teeth.......well the larger pinion at the bearings of the 742/489 would be an advantage.
 
This has nothing to do with the original question but I have seen many original 489 cases with a 7260 yoke. 10 and 29 spline alike. I have seen more 741 cases with a 7290 yoke than 489's or 742's.

Apparently there is a way to use 741 gears in a 489 case because I once bought a 489 not knowing it had 741 gears in it. Wish I would have written down the bearings and races used but I didn't
 
fishy68 said:
This has nothing to do with the original question but I have seen many original 489 cases with a 7260 yoke. 10 and 29 spline alike. I have seen more 741 cases with a 7290 yoke than 489's or 742's.

Apparently there is a way to use 741 gears in a 489 case because I once bought a 489 not knowing it had 741 gears in it. Wish I would have written down the bearings and races used but I didn't
Click to expand...
Well the 741 and 489 use the same bearing race on the small end, M88048. I never checked but the large bearing races may be the same outside diameter? I don't know I'll have to check.
 
Well according to this, the outer pinion bearing and race/cup are the same between 741 and 489. It's just finding the larger bearing that will fit on a 489 shaft but fit the smaller race/cup. I don't think it can be done. The way yours was done 741 ring and pinion in a 489 case you would only need to find a race/cup that was thick enough to fit the larger hole.

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Moparts Tech Archive
Rear Axle
Rear End Bearings & Seals Part Numbers

Rear End Bearings and Seals
By the way, these are National seal numbers, and BCA bearing numbers. Dennis

8 3/4" 3rd member bearings.

741 case
Differential 57-early 69: 25590/25520
Differential Late 69-74: LM104949/LM104912
Pinion inner: HM89446/HM89410
Pinion outer:M88048/M88010
Seal: 8515N

742 case
Differential : 25590/25520
Pinion inner: HM803149/HM803110
Pinion outer: HM89443/HM89410
Seal: 7216

489 case
Differential: LM104949/LM104912
Pinion inner: M804049/M804010
Pinion outer: M88048/M88010
Seal: 5126
 
Well was hoping someone would come up with the magic bearing race for installing the 742/489 gears into a 741........
If i ever come up with such an animal i will sure update this thread.
But for now, have a 489 house coming my way and have ordered 3.91 ring and pinion,bearing, crush sleeve eliminator, Doc Diff stock length axles with Green bearings.( my stock ones have been hammered on for close to 20 year now. (think i'm living on borrowed time with them.)
 
trying to fit a fatter shaft into a small hole-not easy. the 741 inner race has an o.d. of 3.0", and the 742 and 489 inner race o.d. = 3.5". I searched and did not find a race/bearing with a 3.0" o.d. and 1.750" or 1.875" i.d. a custom batch of bearings could be made, what would the minimum quantity and price be? I wonder if anyone has looked into this? can the inner race 3.0" bore of the 741 case be machined out to 3.5"? I think there are enough 742 and 489 cases around so forget about it.
 
cosgig said:
I have a 742 case in my convertible with the 7260 u joint!!
Click to expand...
7260 is the smallest yoke of all three yokes available, but you can put that on all three pinion/housing as long as they are the same spline count Aka coarse or fine spline.
 
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