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np205 HELP HELP HELP

Discussion in 'The Garage' started by brandenbmx, Jan 2, 2007.

  1. brandenbmx

    brandenbmx Registered Member

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    Location:
    Ohio
    Hello,
    My name is Branden Jones I own a 1980 K10 Chevy Truck. My truck has a stock np205 transfrercase,
    and a stock Th350 Transmition. I just reciently baught a 2 wheel 700r4 transmition. I have done alot of research
    on converting the th350 to 700r4 but I belive I have done too much because I dont understand what all I have read.
    I have read so much that counterdicts eachother that I dont know what is right.
    I understand that the th350 is apx. 22 inch long and the 700r4 is apx.23.6 inch long. I measured this myself
    So either the Xfer case needs to be moved back to compensate with the motor location and the rear drive shaft
    will need to be shortened and the front shaft will need to be longer or the motor mounts will need to be reloacted.
    I understand all this. Where It gets a little fuzzy to me is the spline alighnment. The sock th350 is a 27 spline?
    So what is the stock 205 xfercase? What needs to be done to the 700r4 tranny to bolt up to the np205 xfercase.
    I have read about if it is a xfer case that bolted to a th350 the splines in a 700r4 will mesh perfect it will just need to be shortend. I have also read that
    Advance Adapter makes a output shaft that is needed to be installed in a 700r4 to meet the splines with a np205.
    So what is right? Also There is a adaper plate to mount the stock th350 to np205 plate to the 700r4? From what I
    measured on my 700r4 after the tail housing is unbolted the 4 bolt pattern is the same as the stock th350 to np205
    adapter. So my 700r4 will bolt directly up to it. why is a adapter plate needed?

    MY PLANS ARE ...... Unblot the tail housing off of my 700r4 bolt it to my np205 Leave my np 205 in stock location
    leave my drive shafts in stock locations. Move my engine the app amount foward to compensate for the longer tranny
    by relocating the motor mounts. Sounds like a better way to me because it solve the problem with the distributer
    sitting directly up against the firewall, and I dont have to have special drive shafts made. SO with all that said
    what exactly do I need to have the output shaft from my 700r4 tranny to "line up" with my np205?
    I am by no means a tranny guy, I am not going to tear down a 20k mile 700r4 to change a output shaft that
    might just needs cut down? Also are the splines the same or not? If this is going to be to big of a project
    I need to get a xfer case that will bolt directly up to my tranny and then get custome made drive shafts????
    can someone please tell me where I am wrong and where I am right and what I need.
    If someone can I will do a DIY with pics for everyone to reference,
    Thanks in advance
    AHHHHHHHHH this is driving me nutz!!!!!
     
  2. BKinzey

    BKinzey 1/2 ton status

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    the 350 to 205 adapter should work for the 700r4 but you will have to change the input on the 700r4 to the longer 4x4 one.

    At least that's what I've gotten out of researching the same thing.:D
     
  3. adamforsythe

    adamforsythe 1/2 ton status

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    wow thats a can of worms. hahah I think it would be a lot easer to have new shafts made up. moving the engine forward is a lot of work. pulling the engine and tranny grinding down the rivits on the crossmember then redrilling your frame and making sure everything is right on. But if you think you can do it have at it. Just to let you know if you end up getting new shafts. I will buy your old ones.
     
  4. bdozeraz

    bdozeraz 1/2 ton status

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    The splines on the 700r4 are the same as the th350. the output shaft is longer. You either need to replace it with the one from advanced adaptors or get the adapter plate that takes up the extra space so you can use the trans as is. I used the two wheel drive 700r4 with the shaft from advanced on mine. That way gives you the shortest drive train. If you use the adapter plate the trans ends up 5 inches longer. The bolt pattern on the back of the housing of the 700r4 is the same as the th350 but the bolts are metric not standard. If you use standard 3/8" bolts they will fit but strip out.(don't ask how I know)
     
  5. brandenbmx

    brandenbmx Registered Member

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    Location:
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    THANK YOU,
    I called Advanced Adapters today the output shaft kit is like 172.50.

    I talked to this dude Theian, for like 15 min and he ended up telling me that it is just a shorted shaft that is splined furtherback. He didnt tell me the difference but from talking to my local chevy parts department the th350 is 3 inch shorter than the 700r4 output shaft and the 700r4 has splines only 3 inch back so I want to cut mine down and respline it.

    I have family that owns a machine shop shop, so It wouldnt be a big deal... I just dont want to tear down the tranny to shorten the shaft

    Is It possible to shorten this shaft and respline it without disassembling the 700r4???.

    the 700r4 is a 20k mile tranny and I dont want to go digging into a tranny that isnt broke. lol

    Any ideas
     

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