68 Fury lll Fasttop

[ofb383]

Good morning / evening, new to your site, living in the UK with my 68 Fury and have a rear axle question for you all, I don't seem to have what is deemed a usual 8 3/4 back end !
from various searches there seem to be 3 main identification numbers, 741,742 and the other one ? I don't seem to have any of them, my numbers ( not in the usual place either ) are 2467.199 and the casting seems to have different webs , when I rebuilt the rear brakes all the 68 Fury parts went straight on, I believe the car to have been untouched, completely stock when I got her last year.
I'm try to identify the rear end to buy different gear set - ring and pinion.
So, whats going on here ? whats your thoughts?
My rear end is the oily one, the other is what seems to be more common and is a 41 or 42

 

[swartzed]

clean that up better, it may be a 489 which I believe is "the good one"

 

[swartzed]

from Hemmings:
Casting numbers 2070742 (used from 1961-1969) and 1634985 (used from 1957-1964) identify the 1 3/4-inch-diameter 10-spline pinion shaft, and are commonly referred to as the “742” case.

Casting numbers 2070741 (1964-1972) and 1820657 (1957-1964) identify the smaller 1 3/8th-inch-diameter, 10-spline pinion shaft, and are often called the “741” case.

Casting numbers 2881488 and 2881489 were used from 1969 through 1974 and were the only cases used after 1973. This is the most sought-after 8 3/4-inch version, and is called the “489” case. The pinion shaft diameter on these rear ends was 1 7/8 inches, and these pinion shafts were either 10- or 29-spline.

If your differential is original to the car, it can't be a 489 according to Hemmings. I don't know about the stamping being different on yours, I have never seen it.

 

[ofb383]

from Hemmings:
Casting numbers 2070742 (used from 1961-1969) and 1634985 (used from 1957-1964) identify the 1 3/4-inch-diameter 10-spline pinion shaft, and are commonly referred to as the “742” case.

Casting numbers 2070741 (1964-1972) and 1820657 (1957-1964) identify the smaller 1 3/8th-inch-diameter, 10-spline pinion shaft, and are often called the “741” case.

Casting numbers 2881488 and 2881489 were used from 1969 through 1974 and were the only cases used after 1973. This is the most sought-after 8 3/4-inch version, and is called the “489” case. The pinion shaft diameter on these rear ends was 1 7/8 inches, and these pinion shafts were either 10- or 29-spline.

If your differential is original to the car, it can't be a 489 according to Hemmings. I don't know about the stamping being different on yours, I have never seen it.

Same here bud, I've found quite a lot of info, but mine doesn't match anything I've found so far !

 

[Davea Lux]

In any case, you need to figure out where all that oil is coming from and repair the leak. Looks like it is leaking from both the pinion seal and the 3rd member mount to the housing. If the pinion seal is leaking, you can measure the size of the input from the inside of the yoke when you remove it. There were some aftermarket units supplied by third party vendors that did not have Mopar numbers on them and I suspect that is what you have.

Dave

 

[Davea Lux]

You might also want to check your rear brake hose as it does not look to be properly seated in the bracket. There is normally a hex lug on the end of the hose to retain the hose tightly in the bracket so that the steel line is not flexed by movement of the hose. Some of the replacement hoses made overseas do no have the lug and hose will float in the bracket.

Dave

 

[ofb383]

In any case, you need to figure out where all that oil is coming from and repair the leak. Looks like it is leaking from both the pinion seal and the 3rd member mount to the housing. If the pinion seal is leaking, you can measure the size of the input from the inside of the yoke when you remove it. There were some aftermarket units supplied by third party vendors that did not have Mopar numbers on them and I suspect that is what you have.

Dave

Third party units ! why in the hell would they do that ? going to prove interesting to swap out the gears , and yes, slight leak but oil leave is OK though and will be addressed

 

[Davea Lux]

Third party units ! why in the hell would they do that ? going to prove interesting to swap out the gears , and yes, slight leak but oil leave is OK though and will be addressed

They were an exact replacement of the stock units. They were mostly sold as complete drop in units. Factory pats should fit once you figure out which style 3rd member you have.

Dave

 

[ofb383]

They were an exact replacement of the stock units. They were mostly sold as complete drop in units. Factory pats should fit once you figure out which style 3rd member you have.

Dave

I guess that will be based on pinion size / spline numbers etc - to compare it to one of the more common units

 

[Davea Lux]

I guess that will be based on pinion size / spline numbers etc - to compare it to one of the more common units

Once you get it cleaned up, it might have the numbers stenciled on the unit or stamped on one of the flanges, the replacement units were usually marked someplace, but nearly all of them were the heavy pinion units that were sold to racers.

Dave

 

[69 300 vert]

318 or /6car? I think that's essentially a 741 carrier.

 

[ofb383]

318 or /6car? I think that's essentially a 741 carrier.

How did you come to this conclusion? How can I cross check?