8 1/4 rear info

[polywideblock]

looking for info on 3rd gen  b body 8 1/4 rears , have been told ( 3 different sources )  that a some point the supply of 8 3/4 rears ran low  at the st Louis  plant  and small black cars got the 8 1/4 rear while bb cars got the 9 1/4 . any truth to this ? documentation ?

also looking for detail pics( factory markings etc )  of 3rd gen  b body 8 1/4 rears  like this one of the rt's rear
                                                                   

                                                          thanks

[Mike DC]

 
I'm not up on my 3rd-gen info.  But I recall that the 8.25" rear became standard equipment on most SB cars back in 1969.

[Kern Dog]

Not sure, but that picture looks like a Dana 60.
The 8.25 was the default standard axle for all slanty and 318 cars.

[polywideblock]

    it is a dana, looking for 8 1/4 pics showing factory markings etc  like in the pic  of my dana .

     I   have a supposedly original 8 1/4  3:23 lsd under my71  roadrunner (340 4 speed  , 504 build date  )  .

             

  have been asking around quietly for a while now( since I started the resto )  and that's how I got the story about the st Louis plant   running out of 8 3/4 diffs

[John_Kunkel]

have been told ( 3 different sources )  that a some point the supply of 8 3/4 rears ran low  at the st Louis  plant  and small black cars got the 8 1/4 rear while bb cars got the 9 1/4 . any truth to this ? documentation?

I'd say B.S. to the low supply story, the 8 1/4" was purposed to be used in medium-performance applications like the SB and 2-barrel BB's because it was cheaper to build than the 8 3/4".

[RallyeMike]

I agree with John here. The 8-1/4 saw use even in 2nd gen Chargers behind small blocks and 383 2bbl. The story is certainly BS for your RR because they certainly would have prioritized a car with a performance engine to use the 8-3/4 and short-changed the numerous big block and small block non-performance cars first by swapping in 8-1/4's for 8-3/4's first.

[polywideblock]

so is the story BS      or is the 8 1/4 diff not  right for my car , it was sold as having original driveline  including the 8 1/4 diff .

I found two build sheets in the car but both were for other Plymouths one RS23 and the other RP23  so have no way to verify the facts 

[RallyeMike]

About as close as you can get would be to pull the diff cover and see if the ring gear date is in the correct range. Unless the date is after your car build, or significantly before it, you will never know for sure without the build sheet.