What Tranny do I have

Discussion in 'GM Powertrain' started by Michael Johnson, Mar 4, 2011.

  1. Ok, I've been busy reading all of the forums that I can but I keep coming up with a problem with deciding what tranny I have. According to the RPO codes in the glove box per the Compnine.com website I have a 700R4/4L60 but in reading the forums these two seem to be different trannys. So do I have a 700R4 or do I have a 4L60? Or is the 4L60 just a version of the 700R4? Sorry if this is a dumb question but frankly the only trannys that I am familiar with are the old 350 and 400 turbos.
     
  2. 2COR517

    2COR517 Epic Member 5+ Years 1000 Posts

    700F4 and 4L60 are the same trans.
     
  3. Crawdaddy

    Crawdaddy ↑↑↑ Has no life Staff Member 5+ Years 1000 Posts Platinum Contributor

    The 700R4 and 4L60 are the exact same name for the transmission. In 1988, the C/K pickup trucks changed their bodystyle to the new "90s bodystyle". When the bodystyle changed, the 4L60E transmission was introduced. It was the same thing as the 700R4, except that it was electronically controlled by a computer. To keep up with their new naming scheme for the R/V Suburbans, which kept the old 80s bodystyle until 1991, they changed the name of the 700R4 to 4L60 (note the lack of the "E"). Same transmission, new name. The 700R4 is controlled through a throttle valve cable (tv cable). The only electronics in it is for torque converter lockup and reverse light switch.

    In general, it is much safer to refer to your transmission as a 700R4 rather than as a 4L60, though 4L60 is the proper name for 1991. When people hear 4L60, they instantly think of the 4L60E, and common changes made for the 4L60E, like shift kits, are drastically different than the 700R4s. The 4L60E shift kit is a computer reprogramming, which obviously won't work for a transmission that has NO computer control in it.

    So yes, you do have a 700R4... Clear as mud?
     
    Last edited: Mar 4, 2011
    1 person likes this.
  4. 1991 Suburban

    1991 Suburban Rockstar 100 Posts

    You have a 700R4.
     
  5. Actually that does help. I completely missed the E part of the 4L60 but I guess I do remember reading something about the electronic shifting. Anyway thanks for the info. I just have fallen in love with this beast and it's like every new hobby, you want to know everything about it.
     

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