1. 70plygtx

    70plygtx Member

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    anyone know what the standard rearend gear for a 1970 440 GTX was factory? Had this car for 8 years and yesterday was the first time I drove it more than a couple miles. It has 4.10 gears and is clearly way too much. Which I knew it would be. What the car has when I bought it. Just looking at possibly changing in the future.
     
  2. tnfastback

    tnfastback FBBO Gold Member FBBO Gold Member

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    Most likely 3.23 unless it had a special order axle package.
     
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    • 33 IMP

      33 IMP Well-Known Member

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      Dana or 8 3/4? Stick or auto? If a dana, 3.54 sure grip standard, 4.10 optional.
      Hemi, 440-6, 440-4?
       
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      • mopar 3 B

        mopar 3 B Well-Known Member

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        If you want to change it what difference does it make? If the engine likes it do it.
         
      • Wietse

        Wietse Well-Known Member

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        What size radiator do you have? 22" or 26" Do you have A/C?
        If you have a 26" radiator and no A/C you car could have been equipped with a axle package.

        Mine has a 4.10 rear, but the car was originally with a 22" radiator and a PO made a 26" fit.
        They did never change the speedometer gear in the transmission which was a teeth count for a 3.23.
        Guess also the 3.23 was standard for 440's.

        My future plan is also change it, either a 3.23 or a 3.55.
         
      • Photon440

        Photon440 FBBO Gold Member FBBO Gold Member

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        From the 1970 sales brochure:
        upload_2019-7-6_1-6-12.png
         
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        • 66Satellite47

          66Satellite47 FBBO Gold Member FBBO Gold Member

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          An actual GTX only had the 440, 440-6 & Hemi as engines and had the performance axle package 8 3/4- 3.55 or 4.10 Dana 3.54 or 4.10. IIRC 4 spd's all had Dana's either 3.54 or 4.10. 727's could have either 8 3/4 or Dana & either gear ratio.
           
        • 70plygtx

          70plygtx Member

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          Thanks for all the info!
           
        • lewtot184

          lewtot184 Well-Known Member

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          3.23 if it's an 8 3/4.
           
        • 70plygtx

          70plygtx Member

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          440-4 / Dana / 3-spd is what i have.
           
        • Wietse

          Wietse Well-Known Member

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          Do you have a 22" or 26" radiator??
           
        • Dennis H

          Dennis H FBBO Gold Member FBBO Gold Member

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          Did ANY automatics get Dana? Post 6 says no for 70.
           
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          • 33 IMP

            33 IMP Well-Known Member

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            A12s did. I don't know for 70, but i suspect they were available for hemi / 440-6 autos at least.
             
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            • Wietse

              Wietse Well-Known Member

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              In the list it doesn't state anything about Dana's, maybe they were available for both but not mentioned for manual as well as automatic?
               
            • Photon440

              Photon440 FBBO Gold Member FBBO Gold Member

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              the 4.10 option on the last line is a Dana. In 1969 Chrysler found that the 3.91 8.75 wasn't strong enough. In fact, broken 3.91 rears coming in for warranty work had Dana 4.10 replacements installed. Oddly enough, the paper mentions ROAD RUNNER AND G.T.X. EQUIPPED WITH 383 C.I.D. 4-BBL. ENGINE AND 4-SPEED MANUAL TRANSMISSION, something that wasn't in a GTX.
              upload_2019-7-6_11-31-22.png
               
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              • 66Satellite47

                66Satellite47 FBBO Gold Member FBBO Gold Member

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                The sales brochure in #6 is for ALL Plymouth models. No slant 6's in GTX's. Road Runners standard was 383 "Magnum", optional were 440-4, 440-6 & 426 Hemi. Standard for GTX's was a 440-4, 440-6 & optional 426 Hemi. Dana's were certainly available behind 727's as well as 4 spd's in 1970. Track Pak axle package had the 3.54, Super Track Pak had 4.10.
                 
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