[RedDirtRoad]

I will admit. I know nothing about rear axles.
This came with the car I am currently restoring.
I highly doubt its the original axle since there is no visible code and the PHS says
this car had a standard 2:73 Rear
I am assuming this rear now is a 3:55
I spun the rear drum 1 revolution and the pinion spun a tad over 3.5.the carrier?
I dont know if its a limited slip or not. Anyway you can tell by
Housing is Casting # is 9788347
I cant find any info online with this casting number

[b-man]

It’s a limited slip diff, just by looking at it I can see that. If you turn the pinion flange and both rear axles turn the same direction you definitely know it’s a posi rear even with the cover still on.

The gear ratio can also be determined by looking at the numbers stamped in the ring gear and doing some simple division.

[Scott Thelander]

and it aint a freeway 256 gear with those big ring gear teeth ....

[RedDirtRoad]

I found the code on the axle tube
Its ZH which means its either a 1965 or a 1968 3;55 Nodular Iron 4 pinion design
Is there anyway to tell the difference from a 1965 and a 1968 rear?
are the overall dimensions the same or different on both years?

[242177P]

65 is narrower, but for an even easier ID look at the spring perch. 66 and earlier had a flat surface, spring was bolted on with a retainer. 67 and later used an inverted pocket to locate the spring (no bolt)

[RedDirtRoad]

thanks..
of course! I knew that but didnt even think of that.
must be a 68 rear then
So the length and dimensions are the same then?

[b-man]

The ‘68 rear is 1” wider overall compared to a ‘65 rear.

[RedDirtRoad]

Thanks for that info
I have a 67 so this rear should be same dimensions then.
I been reading that 4 pinion rears are heavier duty too over the limited slip with springs in the carrier
Any truth to this?

[Kenth]

4 pinion gears are stronger than 2.
And, there is preload springs in the 4 pinion units too.
Nice find, BTW.