Rear End Question

[MJS73]

Excuse the dumb question, but I'd never really given much thought to the rear end in my car, because I'd always assumed that, being a '73, it was a lower-end 8.75 (like a 742) and would need to be upgraded.  Anyway, while the car was in the air yesterday I went and looked to see which case I have and I took this photo:



Does this mean it's a 489 case?

Also, while it was in the air I spun the wheels to find that both wheels spun together so, barring worn-out clutches or something, does this mean it's a SureGrip?  Is there any other quick way to identify a SureGrip?

Mike

[Kapteenikosmos]

I think that all -73 and up cars came with 489 rears. I'm not sure if the -72 came too but anyway. If your both tires spun the same direction while you turned the other one, then yes you have some kind of locker there. Assuming that the rear end is original to the car and your car seems to be a rallye(?), it has a cone style sure grip. I'm not sure about the gears but I would guess that it has the pretty standard 3.23 "performance" gears in it.

[Chryco Psycho]

if they both spin the same direction it is a sure grip , 489 carriers were used after 69

[MEK-Dangerfield]

It sounds like you got some good news here.   


That beats the one leg rear.

[MJS73]

It sounds like you got some good news here.   


That beats the one leg rear.

You bet.  I was glad to see that.  I believe that it's a 2.76 rear, but I haven't spun it to verify that yet.  The maker of my cam suggests a 3.55 rear gear, but I do drive on the highway 20-50 miles at a time sometimes, so I'm wondering if a 3.55 is too much?  Maybe compromise at 3.23 (if not already)?

Mike

It's not a

[Chryco Psycho]

just count the # of turns of the driveshaft to make 1 rotation of the tires assuming both turn equally

[moparmaniac59]

I don't think Chrysler offered the 2:76 interstate gear with a sure grip/posi unit.




                                                                  Matt B.

[422STROKER]

I had a 2.94 sure grip in the past.

Tom

[FJ5_440]

I don't think Chrysler offered the 2:76 interstate gear with a sure grip/posi unit.




                                                                  Matt B.

I have a 2.76 sure grip out of a 69 sport satellite.  That thing had some decent top end.

[Chryco Psycho]

you could option sure grip into any ratio
 I had a Dodge Van short box with a 318 /833OD/9 1/4 3.5 sure grip diff at one point 

[bb71challenger]

I had a 2.94 sure grip in the past.

Tom

I have a 2.94 sure grip in my Challenger right now out of a 68 Imperial. I have never seen a 2.76 with sure grip but that is not to say that they didnt make it. The one that really freaked me out was a 9.25 out of a 76 Cordoba that had 2.14 gears in it! Man that thing was long legged.

[moparmaniac59]

Well slap me silly!! You learn something new everyday!! I lernt something today!!


                                                      Matt B.

[Moparal]

Could you hold one tire and turn the other tire? 

[MJS73]

I don't know, the car is in storage now.  My testing will have to wait until spring.

Mike

[black71]

I think that all -73 and up cars came with 489 rears. I'm not sure if the -72 came too but anyway. If your both tires spun the same direction while you turned the other one, then yes you have some kind of locker there. Assuming that the rear end is original to the car and your car seems to be a rallye(?), it has a cone style sure grip. I'm not sure about the gears but I would guess that it has the pretty standard 3.23 "performance" gears in it.

i am almost sure that 72's had the 489 as well....