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Axle id # info

Discussion in 'Chevy Trucks' started by TRUP, Nov 19, 2002.

  1. TRUP

    TRUP Member
    Messages: 38

    I assume that if I read off the axle id numbers on my K20 to somebody in a Chevy dealership parts department that I'll find out what the gear ratio is. What other tidbits of information can I expect to get from these id numbers?
  2. paul soccodato

    paul soccodato Senior Member
    Messages: 430

    why dont you just mark the tire and yoke and turn it one time?
  3. TRUP

    TRUP Member
    Messages: 38

    Physically checking the size of the gear ratio is no big deal (4.11). I was hoping to find out if it has a posi or a limited slip. I've dealt with both types of diff's before in Ford's & Jeeps, and the tractive capabilities of this K20 are the smoothest & strongest I've experienced so for. I was hoping NOT to have to take off the diff covers to find the answer to my question. THANX.:)
  4. Chuck Smith

    Chuck Smith 2000 Club Member
    from NJ
    Messages: 2,317

    Look in the glove box. The options decal might still be there. My K/20 listed RPO G80 - Locking Differential. You can also contact GM Customer Assistance, and request a restoration packet. I don't have the number handy, but if you do a search on my Chevy Truck Pages the phone number wil come up.

  5. paul soccodato

    paul soccodato Senior Member
    Messages: 430

    most likely it has a locking diff. i would pop the cover off and take a look, youll feel better when you put new gear oil in anyway.my 84 k-20 had the locking diff.
    ps posi and limited slip are the same thing, positraction (a term gm came up with) is a limited slip diff, what your thinking is called an open diff.
  6. TRUP

    TRUP Member
    Messages: 38

    What I meant by posi was an OEM locker. The after-market lockers on my other two rigs are harsh and somewhat noisy when completing a turn, and the factory limited-slip in a pair of Ford's I used to own were worthless. As I had alluded to in my previous reply, the axles on my K20 are perfect. Thanks for all the info.:)
  7. sonjaab

    sonjaab PlowSite.com Addict
    Messages: 1,425

    TRUP...Take down your RPO codes located on the
    sticker in glove box. Then go to www.gmforums.com
    They have a RPO decoder link that will tell ya what ratio
    you have............geo