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14 bolt FF with locking diff. Fluid?

Discussion in 'Differential & Driveline' started by Jethro224, Jun 15, 2020.

  1. Jethro224

    Jethro224 Full Access Member

    Posts:
    58
    Likes Received:
    51
    Joined:
    May 11, 2020
    Location:
    Illinois
    First Name:
    Jim
    Truck Year:
    1980
    Truck Model:
    K20
    Engine Size:
    350
    Does a 14 bolt full floating rear with factory locking diff use GL5 80w90?
    1980 K20.
     
  2. Jethro224

    Jethro224 Full Access Member

    Posts:
    58
    Likes Received:
    51
    Joined:
    May 11, 2020
    Location:
    Illinois
    First Name:
    Jim
    Truck Year:
    1980
    Truck Model:
    K20
    Engine Size:
    350
    The guy at the part store said that's what to run. I couldn't find anywhere that specified locker or open so that's what I'm doing.
     
  3. Bextreme04

    Bextreme04 Full Access Member

    Posts:
    277
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    242
    Joined:
    May 13, 2019
    Location:
    Salem, OR
    First Name:
    Eric
    Truck Year:
    1980
    Truck Model:
    K25
    Engine Size:
    350-4bbl
    The G80 in the 14 bolt does not need any kind of additive as far as I know. Mine is open, but I also just run standard GL5 80w-90
     
  4. Jethro224

    Jethro224 Full Access Member

    Posts:
    58
    Likes Received:
    51
    Joined:
    May 11, 2020
    Location:
    Illinois
    First Name:
    Jim
    Truck Year:
    1980
    Truck Model:
    K20
    Engine Size:
    350
    Thanks for the reply. I can't find much info on the locking rear.
     

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