Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

th400/np208 output shaft lenght

Discussion in 'The Garage' started by fredo, Dec 29, 2005.

  1. fredo

    fredo Registered Member

    Joined:
    Jul 19, 2005
    Posts:
    12
    Likes Received:
    0
    Location:
    Corsica, France
    I am getting a TH400 rebuilt, They are asking me what's the length of the output shaft is on the current th400. The 400 is mated to a np208. Can anyone tell me what the lenght of the shaft is? is there an easy way to mesure it without getting the tranny down first? Any help would be greatly appreciated as I have to get it shipped oversea. Thanks
     
  2. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

    Joined:
    Feb 7, 2001
    Posts:
    3,103
    Likes Received:
    0
    Location:
    Richmond, VA
    A quick search dug this info up rather quickly...

    From the ORD website:

    GM TH400 Automatic Transmission:
    If you have a TH400, there are three options for mating the 203 to your trans.

    1: Use a factory configuration. The TH400 was available with the NP203 in heavier duty trucks (3/4 and 1-ton generally) in approximately '78-'79. The factory configuration uses a 1 3/8" stickout 32 spline shaft in the TH400, a 32 spline input gear in the NP203 and a 1.1" adapter plate between the two, somewhat similar to the TH350 adapter plate. This is the shortest way to mate the TH400 and NP203.

    2: Use a TH400 that originally had an NP208 mated to it. This TH400 uses a 32 spline shaft that sticks out of the case about 2.5" and has an adapter housing that's about 2.5" thick. You'll use a TH400 version 32 spline input gear in the NP203 and re-drill and tap the face of the NP203 with the round bolt pattern to match up to the NP208 adapter housing. Benefits of this kit are the parts are quite common since the NP208 was very widely used with TH400 trannies. The drawback is the adapter is about 1.5" longer than the shorter factory configuration.

    3: Use a TH400 that originally had a NP205 behind it. This TH400 uses a 32 spline shaft that sticks out about 4.5". You'll need to use a factory TH400 to round pattern NP205 adapter housing that is 4" thick and once again, re-drill the front face of the NP203 to match the round pattern. The input gear will be the TH400 version NP203 32 spline input. Drawbacks to this system are the overall length with the 4" housing between the two and the expense of buying the factory housing. They're not common as used parts and typically must be purchased new. ORD can supply this adapter.


    The only version that's not talked about here is the later models with the round pattern NP205. IIRC, this 205 had the long input but used the same 2.5" shaft stickout as the 208 version.
     
  3. fredo

    fredo Registered Member

    Joined:
    Jul 19, 2005
    Posts:
    12
    Likes Received:
    0
    Location:
    Corsica, France
    thanks I had read that but I wanna make sure that's the only lenght they came out with. No need to mesure it for sure?
     

Share This Page