What is the difference Mopar 8 3/4 to 9" ford?

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DusterMex

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What is the difference Mopar 8 3/4 to 9" ford?

Hi, what is the difference between Mopar 8 ¾ to 9” ford, the gear ring and pinion sets and the posi are the same?

Could you add some pics 8 ¾ mopar?


Thanks
 
The 9" has a smaller pinion diameter than all of the 8 3/4's (741,742,489). The 9" has three bearings supporting the pinion were the 8 3/4 has two. The 9" takes about 5% more HP to turn that a 8 3/4 because of the pinion location on the ring gear. The ratios for ring and pinions for a 9" are just about endless while there are not near as many for the 8 3/4.

There is nothing interchangable from one rearend to the other.
Chuck
 
Hey on the subject of the 8 3/4, I want to know if I have a housing that has a 489 case in an A body dart, and I get a hold of 742 posi unit, are there issues with the number of splines on the axles? I have seem talk about 30 & 35 spline axles.

I would need to pull an axle to see what I have now, but I think stock are 30 correct?

Thanks!
 
DusterMex said:
What is the difference Mopar 8 3/4 to 9" ford?

Hi, what is the difference between Mopar 8 ¾ to 9” ford, the gear ring and pinion sets and the posi are the same?

Could you add some pics 8 ¾ mopar?


Thanks
Click to expand...

This might help you as far as 8 3/4 rears goes:

http://www.autohobbydigest.com/8_75.html

http://www.moparts.com/Tech/Archive/axle.html

http://www.bigblockdart.com/techpages/875axle.shtml

http://www.bigblockdart.com/techpages/diffchart.shtml

http://www.bigblockdart.com/techpages/drumchart.shtml
 
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