Mopar Ring gear i.d

[ValerianMagnum]

Hi guys , bought a couple of parts to a guy that had a 70 duster , sold the car and i bought some mechanical parts that he had : d-shaft , 741 case , yokes etc , but..he offered me a ring gear and pinion , told me that they were 4.10s...for a old 741 case , i have no idea how to verify that , the gear and ponion are like brand new , barely used . Ring gear has a number on it , but i dont find anything on the net, maybe someone here will guide me ! Thx

 

[rbkt65]

count the teeth and divide the pinion number into the ring gear number. that will give you the ratio. if ring has 41 teeth, the pinion will have 10 teeth, therefore 4.10

 

[ValerianMagnum]

Ok !!! So its a 41 teeth ring and 10 teeth pinion so its = 4.10 ! , all good but...he said it was for a 741 case...seems weird , any way to see if its for a 489 or 741 case ?

 

[rbkt65]

probably measure the diameter of the pinion where the rear bearing rides and you should be able to tell. i forget what the bearing sizes are but someone will come along and probably tell us. i thought 1 3/4, 1 7/8 and ???? 741, 742, 489.

 

[Big.J.007]

1-3/8 pinion diameter is 741, 1-3/4 is 742, 1-7/8 is 489 case

 

[Lefty71]

Too old to be for 489 case??

 

[crackedback]

Same ring gear for all 8.75 cases. No difference in any of them.

Pinion is the only thing to determine case.

 

[33IMP]

741 pinion shaft is straight, same size as the threads for the pinion yoke
742 has a shoulder at the pinion yoke threads, and has a larger shaft.
489 has a funnel-shaped tapered shaft.

 

[ValerianMagnum]

 

[crackedback]

Pinion Comparison - Quality Body Shop Drivetrain

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. 8 3/4″ pinion shaft designs: Notice, all pinion shafts neck...

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