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88 3500 454,, thinking of going to overdrive trans

Discussion in 'Chevy C/K Truck Forum' started by Rhonda36301, Nov 11, 2012.

  1. Rhonda36301

    Rhonda36301 New Member

    I have an 88 3500 4 dr dually. It has a fuel injected 454, th 400 trans, it get really bad fuel miliage. it a really nice truck and runs great.
    i was thinking of going to an 700 r4 or something along that line, anyone done this swap or something similar. what yr trans would i need ? what all would i run into with a swap like this? Gas i killing me. thanks Rhonda
  2. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    I'm not sure a 700R4 would be the best choice for that application, with the torque and HP output of that engine I think you might have transmission reliability issues.
    Have you looked at available add on overdrives?
    Try a search and look at some of the available options, theres a few companies that make add-on overdrives that can handle the power of your big block, yea their gonna be a little more expensive but it aint cheap to buy the adaptor and keep putting in new transmissions either.
  3. grampy

    grampy Member 100 Posts

    An option would be to contact someone like TCI trans., they should have some info on O/D trans for a big block. A relative of mine has a Ford with a swapped in 429 w/a 5sp manual O/D ( the overdrive was awapped in later ), it's a nice driving truck but he's never gained enough fuel mileage over the old 4spd manual to even pay for the parts. You didn't say what you use the truck for but I have to assume you do some heavy towing. We went to a diesel for our towing ( a stock trailer and flat deck gooseneck trailer ) years ago & it was hard to justify. A neighbor of ours went a different way, he has a 3500 /454 just a bit newer than yours. He just leaves the "beast" hooked up to the stock trailer and bought a small block 1/2 ton as a daily driver. Good luck, Ken.
  4. Boonduff

    Boonduff Member 3 Years 100 Posts

    I know several people who have swapped in overdrive trannies hoping for better mileage. Everyone of them has come away disappointed with the results. The cost of the swap cost more then they anticipated, and the gains in fuel mileage weren't enough to justify the cost. A big-block is a gas hog, there is no way to get around it. It's just the nature of the beast.
  5. Conlan Rose

    Conlan Rose Active Member 2 Years 1000 Posts

    The 700R4 is for smaller pickups and suvs not your 3500. The better replacement is the 4L80e which is an overdrive tranny built to handle heavy duty applications. But still that's an almost $3,000 tranny and you would still have to install it.

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