I have a GM TH400 tranny ( HD version ) with 32 spline male shaft that sticks out 4.5" & NP203 reduction box , with 23 spline female shaft , which was installed after a manual Dodge tranny .
I would like to bolt them together in the next way - i'll cut from the tranny shaft 3 cm ( 1.18" ) then machine a female/male coupler which will go from the male shaft in the tranny to the female shaft of the NP203 reduction box.
The problem is , that the adapter plate ( TH400-NP203 ) will get to 8-9 cm ( 3.15"-3.55" ) thickness , this approch seems to me as a bit thick to what i'm planning ( i want to make a doubler and i don't have enough wheel base - only 110" ) .

So , my questions are :
* What do you think about it ?
* Did anybody do this before ?
* Can i change/buy the female shaft of the NP203 23 spline into a female 32 spline shaft which will suit the Gm TH400 32 spline male shaft , and then save the machining process of the coupler ?
* Can i buy a new TH400 main shaft with 23 spline ?

And now to the pictures -

this is the TH400
http://www.4x4.co.il/gallery/gallery_pictures/8720_gallery_640.jpg

http://www.4x4.co.il/gallery/gallery_pictures/8719_gallery_640.jpg
+

This is the main male shaft
http://www.4x4.co.il/gallery/gallery_pictures/8722_gallery_640.jpg

http://www.4x4.co.il/gallery/gallery_pictures/8718_gallery_640.jpg

This is the length of the splines - 70 mm ( i would llike to cut it down to 40 mm )
http://www.4x4.co.il/gallery/gallery_pictures/8728_gallery_640.jpg

This is the female shaft of the NP203 reduction box with the gear
http://www.4x4.co.il/gallery/gallery_pictures/8725_gallery_640.jpg

This is the 23 spline .
+http://www.4x4.co.il/gallery/gallery_pictures/8726_gallery_640.jpg

This is the coupler that i want to machine
http://www.4x4.co.il/gallery/gallery_pictures/8727_gallery_640.jpg



Thanks in advance

Sounds like a lot of brain damage to me. Call Stephen Watson at Offroad Design and he will be able to answer your questions. His # is 970-9456-7777 USA Or www.offroaddesign.com
110" wheelbase is plenty for the "Doubler". I have one in my rig at 106" :D

Stephen at ORD has a doubler kit which replaces the 23 spline 203 part with a new 32 spline part.

You will also need to get the original short TH400-203 output shaft for the TH400, which is a fairly easy part to get from a tranny part place.

Once that's done you have a short 32 spline output out of the TH400 and a 32 spline input on the 203, which allows you to use the 1" thick TH400/203 adaptor.

If you don't want to buy his kit, and still make your own doubler adapter, he may just sell you the 203 shaft.

Call him

Tim.