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Technical chevy rear end casting numbers

Discussion in 'The Hokey Ass Message Board' started by flatheadgary, Nov 1, 2019.

  1. flatheadgary
    Joined: Jul 17, 2007
    Posts: 845

    flatheadgary
    Member
    from boron,ca

    does anybody know of a chart that can give the car a third member numbers relate to. i need to buy some parts for it. it is the type that was used in the '55-'64 chevy cars, and yes i could just say that at the store, but where is the fun in that? i could also take the wheel cylinders to napa and have them look up those numbers, but i don't have much else to say for a thread right now. here they are:
    3707306 GM3
    AB 1007
     
  2. Mr48chev
    Joined: Dec 28, 2007
    Posts: 29,048

    Mr48chev
    ALLIANCE MEMBER

  3. squirrel
    Joined: Sep 23, 2004
    Posts: 48,666

    squirrel
    Member

    they usually have a casting date code, the closest thing to that in your list of numbers is the AB 1007, but that's not the right format exactly for a casting code. If it were A 8 1 it would be Jan 8th, 1961, for example.
     
  4. Penetrator
    Joined: Aug 25, 2011
    Posts: 514

    Penetrator
    Member
    from SK CAN

    According to my friends @ https://www.chevytalk.org/

    3707306 indicates a 1956 differential.

    AB indicates 3.55 ratio, made in Detroit.

    1007 is the date of manufacture, Aug 7.

    Furthermore, I'm with the understanding the pumpkin/diff swaps with several Chevrolet models from 55- 64, Corvettes to 4 door Biscaynes inclusive...

    If all that rings true, you have differential identification, but nothing to define which Chevrolet model it belongs to, which puts you at square one for brake parts.

    .
     

  5. squirrel
    Joined: Sep 23, 2004
    Posts: 48,666

    squirrel
    Member

    Interesting....I didn't know about those other codes. Are they actually casting numbers? or are they stamped? I would expect them to be stamped. I think I've seen normal Chevy casting date codes on the center housing, but I could easily be mistaken.

    If it has the original ring gear in it, that should be stamped with the ratio and date also. Kind of hard to see it without taking things apart. But since the crush sleeves are always worn out, and it needs a new pinion seal, and you have to inspect the pinion for cracked teeth, you're gonna take it all apart anyways.
     
    427 sleeper likes this.
  6. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 1,209

    427 sleeper
    ALLIANCE MEMBER

    IIRC, the 3rd member parts ( bearings, seal, and crush sleeve, etc. ) are all the same between years. The brake parts would be application specific.
     
  7. squirrel
    Joined: Sep 23, 2004
    Posts: 48,666

    squirrel
    Member

    They did change the carrier bearings after a couple years, the early ones had barrel rollers instead of tapered rollers.
     
  8. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 1,209

    427 sleeper
    ALLIANCE MEMBER

    Oh, that's right, they did! My bad. Can't the tapered rollers be retrofitted to the earlier models though?
     
    Last edited: Nov 2, 2019
  9. squirrel
    Joined: Sep 23, 2004
    Posts: 48,666

    squirrel
    Member

    I think so, I don't remember if you need the earlier carrier? probably not real important, in the grand scheme of things
     
  10. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 6,695

    56sedandelivery
    ALLIANCE MEMBER

    Actually, the 55-56 housings are different than the 57, they take smaller axle bearings; the axles are also different. You can put a 55-56 housing in a 57, and vise versa, you just have to know the differences when it comes to parts. The 57 is unique onto itself, then 58 things changed again, but basically stayed the same through 64. Brake parts are pretty universal; the drums are the same 51-58. 57 housing is the only housing with a drain plug. The third members are "swappable" 55-64 full size, 56-62 Corvette, and 62-63 Chevy II/Nova (but the Nova are really light weight assemblies, and use smaller bearings, so don't use them). They are ALL 17 spline axles, seals and crush sleeve are the same. Basically, lots of "little" differences. I am Butch/56sedandelivery.
     
  11. flatheadgary
    Joined: Jul 17, 2007
    Posts: 845

    flatheadgary
    Member
    from boron,ca

    well, thanks for all the replies. yes jim, the ab number is stamped and the other one is cast into it. these numbers are on the face of the diff by the bolt holes. it's pretty dirty so there may be other numbers to. either way, you all have given me what i expected. i will just say it's '56 chevy and then i will have napa look up the numbers on the wheel cylinders for more info. napa is good at that. i needed wheel cylinders for my fed and they looked up the numbers for me. it is a olds, pontiac or impala. early model say '49 or something like that. it is not the big one. it has a genuine m/t magnesium third member though. it also has summers brothers axle. so the small diff doesn't bother me.
     

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