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.

TH400/205 swap questions

Discussion in 'The Garage' started by hi pinion, Mar 7, 2006.

  1. hi pinion

    hi pinion 3/4 ton status

    Joined:
    Sep 25, 2003
    Posts:
    5,354
    Likes Received:
    0
    Location:
    **PLUMBING THE WORLD**
    Ok, i have some qusetions.

    My 74 i just got has a 350/350/203 setup right now.

    Its got a 4 inch lift on it right now.

    Desert Rat replaced the shafts on the truck both front and rear, it has Off Road Design shafts on it, brand new...........



    My qestion is this, if i do the 400/205 install, what do i have to modify?The crossmember? The shafts? Is the 400/205 LONGER than the 350/203 in it now? Also, could i technically find some shafts off of a truck the already HAD a 400/205 in it and make that work easy?

    Whats involved? Also, are all the th400 trannys the same in length/cases? I thought i read some of the th400s were shorter than others :dunno: ,, or mabey it was the 205 i was thinking about.

    Anyways,,,,yeah:laugh:
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,977
    Likes Received:
    189
    Location:
    Roy WA
    Only thing I know about is the TH400's. The length is all the same when talking about the case. Since the adapter on a 4wd is what places the crossmember on the frame, not sure if GM was smart and made the TH400/TH350 length the same with the crossmember in regards to crossmember location, or if they were different.
     
  3. Desert Rat

    Desert Rat Fetch the comfy chair

    Joined:
    Oct 19, 2002
    Posts:
    16,250
    Likes Received:
    3
    Location:
    Tri-Valley, NorCal
    The NP203 is longer than the NP205 (http://www.offroaddesign.com/Transfer%20Case%20ID%20Guide.htm). The TH400 case and the TH350 case are very similar in length. If you swap in the TH400/NP205 combo, it is likely that the crossmember will have to move, but not a huge amount. This will result in the driveshafts (made by Bayshore Truck in Livermore, not ORD :D ) will need to be modified. However, they are new and it shouldn't cost a lot to have a local driveshaft company shorten or lengthen them for you. Or, you can find someone with a TH350/NP203 setup around and sell them to them since they are brand new and then go HAD. I wouldn't use used shafts from another truck with the TH400. I would just have new ones made or modify the ones you have. The easiest way to make the change is to support the engine, drop the tranny and TC. Swap in the TH400 and install the NP205, bolt the crossmember to the bottom of the NP205, jack it up against the frame, mark the frame, drill new holes, and install the crossmember. Then take measurements on the length from the TC outputs to the diffs and see if you can use the existing shafts. If not, modify them or sell them and go new.
     
  4. BranndonC

    BranndonC 3/4 ton status

    Joined:
    Mar 18, 2002
    Posts:
    8,591
    Likes Received:
    0
    Location:
    Anaheim, Ca
    i'm no help since i went straight to a doubler, never just a 400/205, and my 205 is a slip yolk, so my shaft from my 241 worked for it
     
  5. sweetk30

    sweetk30 professional hooker Premium Member

    Joined:
    Nov 1, 2004
    Posts:
    25,537
    Likes Received:
    536
    Location:
    horseheads , ny 14845
    case length from bell to end of case where tail adaptor bolts on

    th350= 21 5/8
    th400= 24 5/16
    th700= 23 3/8
    4l60 to 95= 23 3/8
    4l60 96-up= 21 3/4
    4l80= 26 even
     
  6. hi pinion

    hi pinion 3/4 ton status

    Joined:
    Sep 25, 2003
    Posts:
    5,354
    Likes Received:
    0
    Location:
    **PLUMBING THE WORLD**
    Thanks!!!:laugh:
     
  7. sweetk30

    sweetk30 professional hooker Premium Member

    Joined:
    Nov 1, 2004
    Posts:
    25,537
    Likes Received:
    536
    Location:
    horseheads , ny 14845
    no problem. just poped over to tci and grabed the specs for ya. :wink1:
     
  8. BizeeB65

    BizeeB65 1/2 ton status

    Joined:
    Oct 12, 2005
    Posts:
    859
    Likes Received:
    0
    Location:
    Louisville, KY
    You still have those shafts? Is the rear shaft stock length? Has it been lengthened for the lift? I am looking for a lengthened rear driveshaft for a NP203 to 12B with 6" lift. Interested in selling?
     

Share This Page