differential compatibility

[Damien B.]

I m yet again asking for some information
Are the differential compatible between the 3 different casing for an 8.3/4 third member ?
i have a 489 with a regular open differential with the 4 gears, i have the possibility to get a cheap 742 third member with a suregrip in it.
would it be possible to swap the differentials without any compatibility issues?

 

[multimopes]

As far as I know (or don't know) you shouldn't have any problems except possibly the yoke size, which can be changed.

 

[33 IMP]

Yes. Sure grip and open carriers interchange on all 8 3/4 centers.

 

[R413]

Yes. Sure grip and open carriers interchange on all 8 3/4 centers.

As long as they are 1965 and newer open carriers.

what year is your open rear?

 

[Damien B.]

Thanks for all the replies
I m not sure what year it is i ll go and check the 742 casing this week
I have no idea wich year the one currently on my satellite is all i know the casing is written engraved 489

 

[Fran Blacker]

Look in where axles go to make sure the thrush button is there.I you see a 5/16" or 3/8" hole button is missing, no big deal $30 part.
This doesn't apply to a cone sure-grip.

 

[beanhead]

I m yet again asking for some information
Are the differential compatible between the 3 different casing for an 8.3/4 third member ?
i have a 489 with a regular open differential with the 4 gears, i have the possibility to get a cheap 742 third member with a suregrip in it.
would it be possible to swap the differentials without any compatibility issues?

You can swap the diffs but you must use the proper carrier bearings.
The clutch-type differential in the 742 used bearings with a smaller I.D. but the O.D. of both bearings was the same.

 

[Nate S]

As long as they are 1965 and newer open carriers.

what year is your open rear?

‘64 and newer....

 

[R413]

‘64 and newer....

1964 has the tapered axle shafts, and the 1.25” wide thrust block on an open rear. 1965 was the first year of the flanged axles and they had 1.5” wide thrust block in the open rear.

All 8.75 sure grips had a 1.5” thrust pin or block width in all years.

 

[Nate S]

64 has the tapered axle shafts, 1965 was the first year of the flanged axles.

Yes but the center section is identical. The center section difference open to sure grip ended in the start of the ‘64 model year.

 

[Nate S]

1964 has the tapered axle shafts, and the 1.25” wide thrust block on an open rear. 1965 was the first year of the flanged axles and they had 1.5” wide thrust block in the open rear.

All 8.75 sure grips had a 1.5” thrust pin or block width in all years.

You’re off a year. ‘64 still had tapered ends but open and sure grip had the same center block width.

 

[R413]

This is the first I’ve heard of this. I’ve got 61-62 mopars but never a 64

 

[Nate S]

This is the first I’ve heard of this. I’ve got 61-62 mopars but never a 64

From the '64 parts manual. Note that in the center "dodge/plymouth" column there is only one axle length unless you have the narrower Max Wedge axle.

 

[wvmarv]

Why not just use the 742? They are perfectly fine for just about anything.

 

[Nate S]

You can freely swap the sure-lock / carrier from one to the next with the only exception of a '63 or earlier open center section.

 

[hunt2elk]

742's are nice chunks. They would have come with clutch instead of cone sure grips and also didn't use the crush sleeve. I run one in my Duster.

 

[R413]

We need to know what year his car is. That will tell us if the SG will swap in with no problems.

 

[Damien B.]

My car is a 1971 satellite with a 8.75 rear end. i m not sure about the ratio on the third member it s most likely a 4.56 ratio i did 20 revolution of the tired and counted how manytime the driveshaft turned but i have no idea what the differential is in it
i also have a spare third member (489) with a 3.23 ratio with a basic differential.
Since i have a 408stroker incoming in a few months i would rather put on the 3.23 in order to keep the satellite highway friendly but i would prefer to have a suregrip in it instead of the basic open differential.

i got a lot of info thanks to this thread I will have some more info about the third member i got my eyes on later this week since after calling the women has no idea what her late husband had she just assumed it was a 742 casing

 

[matthon]

To clarify, I cannot take my 64 8 3/4 tapered axle Sure-Grip and swap into it a 62 8 3/4 open center section, correct?

And there's nothing I can change/replace to make this swap work?

To change my 64 to an open I would need a 64 and up open, correct?

 

[hofferwood]

Read this, they changed in '65.

Chrysler 8-3/4" Axle Guide