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th400 to 208 (what does it take to swap out a 700r to a th350)

Discussion in 'The Garage' started by JohnDeere, Feb 11, 2007.

  1. JohnDeere

    JohnDeere 1/2 ton status

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    Will a th400 mate with a 208.


    what does it take to swap a 7004 to a th350
     
    Last edited: Feb 11, 2007
  2. resurrected_jimmy

    resurrected_jimmy 1/2 ton status

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    the quick answer is yes but I'm not sure of the spline count. TH400/ NP208 setup may be a a 32 spline coupling instead of the 27 spline like your 700R4/NP208 setup. TH350/NP208 is not too hard to find though.
     
  3. ryan22re

    ryan22re 1/2 ton status

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    Yes, you need a 400 to 208 adapter and a 32 spline 208. Dunno if there are any different 32 spline 400 outputs, but I think they are all the same (assuming a 4wd th400).
     
  4. JohnDeere

    JohnDeere 1/2 ton status

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    is a 350 any stronger than a 700r or are they the same just an overdrive
     
  5. resurrected_jimmy

    resurrected_jimmy 1/2 ton status

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    I don't have any numbers to put to it but TH350's are much more forgiving and I have had good luck with them. I roasted three 700's before I gave up and swapped to a 350 trans. I have yet to burn up my TH350. The reason I brought up this option is because they are plentiful, easy to rebuild, and cheap. I don't consider a 700 to be at all the same as a TH350 with overdrive.
     
  6. JohnDeere

    JohnDeere 1/2 ton status

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    ok thanks. So if i want to put in a th350 I would have to get one that had a 208 to it and does the th350 have a kick down cable like the 700r. I know the th350 is giong to be shorter than a 700r. does anyone know the length difference. If its less than 3 inch than i dont think i will have to get a new drive shaft.
     
  7. Smokin'Joe

    Smokin'Joe Registered Member

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    When I did my swap, 700 to 350, I had gone to one of my local junkyards. This yard has a guy that rebuilds auto trannies for them. I used my 700 as a core. What I recieved was a rebuilt 350, a new dipstick, converter, detent cable and an adapter. The adapter was, more or less, a spacer to make up the diference in length from the 350 being shorter. Cost me about $550 total. The swap was straight forward with almost no mods needed. The only mod I had to do was the detent cable. With the stock bracket on the motor, it wouldn't reach the tbi. I simply lengthened it,or you could use a new bracket. Rarely do I see speeds to need overdrive. It was also half the cost of a rebuilt 700. I've been driving this truck for five years now.
     

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