What axle ratio probably came in my 73....

Engine, Trans & Driveline

  1. bandit67

    bandit67 FBBO Gold Member FBBO Gold Member

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    Guys, done with cleaning , repainting my underside, got the axle assemble reinstalled today. My car left the factory as a 400, 4 speed. Some body along the way installed an 727 tranny and prolly the rear axle at that time. The shifter and all linkage was OEM. I assume they transferred all from a donor car. I found a tag on the 8 3/4 I believe is the ratio tag, 3.23.
    My build sheet was not readable and I am curious as to what ratio would have come with the 4 speed if someone had NOT made a special order. Was there a standard ratio .....thanks...
     
  2. Oldreddodge

    Oldreddodge Well-Known Member

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    I had a 73 rr 400 4 spud 14 inch road wheels had 3*23
     
  3. #41

    #41 Well-Known Member

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    I would also say 3.23 is the most common.
     
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    • Paul_G

      Paul_G Well-Known Member

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      Another 3.23 in my 73 400 4 speed.
       
    • 400sforever

      400sforever Well-Known Member

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      I have a 73 400 4 speed with factory 3.55 gears and my 74 400 4 speed also has factory 3.55 gears. .both are Charger rallyes
       
    • YY1

      YY1 Well-Known Member

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      72 400-4 Auto

      3.23 SG

      The 2.94 pretty much went away before the 1970-ish time frame leaving the 2.76 the most common ratio, the 3.23 as the entry level performance, the 3.55 as an intermediate upgrade and the 3.91 as the serious performance 8 3/4 gear.
       
    • bandit67

      bandit67 FBBO Gold Member FBBO Gold Member

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      Thanks Guys. My car is a rally car so now I m wondering if the Rally cars got the 3.55 as standard. The current diff is a peg leg, open diff, and wondering if any of those came with a Sure Grip or did that option HAVE to be specified. I think the extra chunk I aquired years ago is a 3.91 so now thinking of sticking that one in. But , having never drove this car will start with the 3.23. I do have a 3.55 in one of my Chevelles and find that to be a really fun play car street gear.
       
    • YY1

      YY1 Well-Known Member

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      Do you have the fender tag?
       
    • bandit67

      bandit67 FBBO Gold Member FBBO Gold Member

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      Yes on the fender tag , very rusted and hard to read, what could /should I look for.
       
    • YY1

      YY1 Well-Known Member

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      Do you know what plant it was built at?

      7th digit.

      If it's a Lynch Road car, the axle ratio will be part of the gate sequences at the top of the tag.

      If it's not a Lynch Road car, it may have a code (starting with "D" IIRC) on the first or second line from the bottom.

      Here's a list of codes, but not vetted by me-

      http://www.mopar1.us/build.html

      if it is a Lynch Road car, we have a resident LR expert.
       
    • Paul_G

      Paul_G Well-Known Member

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      My 73 Rallye 400 4spd has a 3.23 as I stated above. Bottom line of the fender tag is D21. All that means is a HD 4spd Man. When I tried to decode the fender tag, rear gear was not listed.

      The 73 Rallye I used to have years ago, 440 auto, had a 3.55 rear gear. Hard to tell now if either of these cars had the original rear ends in them.
       
    • bandit67

      bandit67 FBBO Gold Member FBBO Gold Member

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      Thanks YY1 for that code post. I am trying to post my fender tag, its in rough shape. I also have D21 on the bottom, but that does not say what gear ratio. BUT, what is the difference in D 15 and D 21, did they offer two four speeds?
       
    • bandit67

      bandit67 FBBO Gold Member FBBO Gold Member

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      My fender tag....thanks Guys, what do I have.....

      IMG_0144.jpg
       
    • YY1

      YY1 Well-Known Member

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      Lynch Road

      numbers on top are the gate sequences, and your axle ratio/SG should be in one of them

      I'm not a gate sequence guy though
       
    • YY1

      YY1 Well-Known Member

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      I think it's the 056
       
    • 400sforever

      400sforever Well-Known Member

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      I will go look at my lynch road 4 speed and see what I've got
       
    • 400sforever

      400sforever Well-Known Member

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      I found some info on those sequence numbers. .my 74 is different because it's a 74..but 056 stood for 400-4 barrel without ac in 73. 988807 stood for axle ratio and transmission .i haven't found 988 but the 807 stands for b body 4 speed. .if your first three numbers were 992 then it would have been a 3.55 gear, so I'm thinking that 988 may have been something like 3.23
       
    • 400sforever

      400sforever Well-Known Member

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      Bingo! Found it! 988 is 8 3/4 3.23 open diff with 10" drum brakes
       
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      • bandit67

        bandit67 FBBO Gold Member FBBO Gold Member

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        Ha Ha awesome, thanks 400s. WOW, would not have thought that info was on the tag, great. I guess if someone decided to make tags that carry that info , someone kept track of it. It is a non AC car as decoded and does the tag support it being a Rally car. So this means I get to drive the car the first time in mostly the factory setup... Now, if it specifies a 10 drum....what other size drum brakes are/ were available.....thanks all.....
         
      • 400sforever

        400sforever Well-Known Member

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        No problem! At least you know how the car was originally setup! Maybe some of them got 11" rear drum brakes but on all the 73/74s I've been around have never had anything bigger than 10"
         
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