Discussion in 'GM Powertrain' started by FordAssasin, Jan 31, 2010.

  1. FordAssasin

    FordAssasin Member

    Hey guys got a tranny question here,Will a 4l80e fit in my 1999 Chevy Tahoe its 2wd as is the tranny but i have the 4l60e? Do I need to get any extra parts/peices or will she just bolt up in place of the old one? The guys is selling two of them one thats 2wd and another thats 4wd i dont know anything bout 4wd just that its heavier duty.Also if i add the 4l80e does my ECM need to be reflashed/reprogrammed? Let me know people so i can swoop on one before its gone he is selling both of them for $275 each they look clean in the pictures and he is selling them with rebuilt internals need to know ASAP!!
  2. Crawdaddy

    Crawdaddy All hail the Mad King!! Staff Member 5+ Years 1000 Posts Platinum Contributor

    A 4L80E is typicall bolted up to a big block, and I doubt you have a 454 in your Tahoe, more likely a 305 or 350. Your PCM would have to be re-flashed to work with the 4L80E at best, or the whole wiring harness could have to be replaced at worst. The only difference between a 2wd and a 4wd 4L80E transmission is the tailshaft on it. The 2wd tailshaft is longer and is designed to connect directly to a driveshaft. Conversly, the 4wd tailshaft is much shorter, and designed to bolt to a married transfer case. So, if you're 2wd and staying 2wd, you need the 2wd version of the transmission. You will need some harness adapters, and most likely need your driveshaft shortened, as the 4L80E is significantly longer than the 4L60E.

    Now that all that's been said, why are you wanting to move to a 4L80E transmission? Have you repeatedly blown up 4L60E transmissions, do you plan to tow and think you need the extra strength, are you just in it to have a heaver-duty transmission? All 3 of those questions can be actually answered by rebuilding your existing 4L60E and putting heavy-duty parts into it. A properly built 4L60E is nearly indestructible and the transmission of choice for hard-core 1/4 mile dragsters because of this exact reason, that and they're cheap and plentiful.
  3. FordAssasin

    FordAssasin Member

    Ok thats why I asked so what would you suggest I do to my tranny to make it more heavy-duty? Also my brother has a 454 that came out of another Tahoe and he said he would sell it to me for $200,He has the wiring harness but what else would i have to do to run the 454?Reflash the ecm? For now i will await further instructions from you on this matter,I get my Tax Return from the IRS on the 12th so let me know what kind of goodies I can buy for the tranny and what else i need to do to swap to the big block,Thanks bro

    TYMBOM Former Member

    I agreed with most of Crawdaddy's post. Depending on what you are planning on using your truck for, the 4L60 could be made to do it. However, the hardcore racers do swap to the 4L80 because of their strength. I went through five 60's and know of others who went though even more. I love my 4L80 and wish I had done it at first.

    That being said, there is a lot of other mods and a lot of money to do the swap. I bought a Finish Line Transmission and swear by them. They make both in different levels.

    It's up to what you wan your end result to be and how much you are willing to spend on doing it. Hope that helps some.
  5. FordAssasin

    FordAssasin Member


    When i bought the Tahoe my father insisted on getting a US Fidelis auto warranty cuz of the expensive nature to replace parts and do work on my Tahoe there is one on craigs list for $385 looks clean and i know thats cheap as hell!!The only reason why im wanting to do some tranny work/swap is due to the fact that the 1st to 2nd shift is a little on the hadr side but the 2nd to 3rd and 3rd to 4th is great,So with being said how hard would it be to drop a T56-6speed in my Hoe? That would be crazy there is some more food for thought and i just want to thank you guys for all the great advice I LOVE THIS SITE!!! Let me know about the 6-speed

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