Help identifying my differential

-
M

moondust74

New Member
Joined
Jan 11, 2021
Messages
2
Reaction score
0
Location
Ontario
Hello everyone, this is my first post - been reading here a lot and get most of the answers I need. This one has me stumped. My car is a 74 Duster with 727 auto and I'm trying to find the right speedo gear as my car has none and leaks a lot there. I jacked up the car, spun the wheel and counted drive shaft rotations. 2 wheel turns - 2.4 (estimated) drive shaft rotations. Wait, this doesn't line up with any gear ratios I can find on any mopar charts! So I popped off the diff cover and counted teeth, 20 to 49. That's 2.45:1. This number is also stamped on the ring gear. So, I'm assuming this is not a mopar rear end? The housing looks like a GM 10 bolt as per this thread;

Mopar Rear End need help to identify

If that's the case, and if someone can confirm that, what was all changed in order to make that work in my car... brakes, driveshaft, etc? Thanks!

IMG_20210628_203616.jpg


IMG_20210628_203638.jpg
 
Christ!!! That cover looks like a GM 10 bolt??

As for "what changed" no idea. Someone may have welded Mopar ends on a GM housing. Who knows what brakes. They obviously welded on spring perches.
 
Welcome!

Now a lot can be changed on a car 46 years later but if it was born with a 8 1/4 and a 727 from the factory, it should also have a 360?? What are the details on your Duster? We love pictures!
 
It's an 8 1/4 with 2.45's, as others have said. Lots of them out there back in the day.
 
Thanks everybody. I couldn't find 2.45 on any of the speedo pinion gear charts - 2.76 is the minimum on them. If 2.45 is common, then that makes sense but the cover of my 8 1/4 does not have a fill hole and the pictures I've found typically have a flat top and bottom. Mine is pretty round.
 
moondust74 said:
Thanks everybody. I couldn't find 2.45 on any of the speedo pinion gear charts - 2.76 is the minimum on them. If 2.45 is common, then that makes sense but the cover of my 8 1/4 does not have a fill hole and the pictures I've found typically have a flat top and bottom. Mine is pretty round.
Click to expand...

It's an 8 1/4.
 
You must log in or register to reply here.
-

Back
Top