NP203 input shaft swap? (Suburban)

[Johhny]

Hey everyone, hope someone can help me out with this,

I got a '79 4x4 Suburban with a 400ci, th400 and a np203 transfer case. The np203 broke a while ago (worn chain) so I got myself a new one from a '78 Sub.

After removing the old np203 and installing the new one it appears to have a different input shaft. After some online research I discovered that apparently:

np203 for a th400 = 32 spline input
np203 for a th350 = 27 spline input

Since the old one only has a worn chain I was wondering if I can swap the input shaft to the new case? Did anyone did this before? What steps are needed? Will the axles still fit?

Since most Subs here are 2wd it was already hard to get a GM np203, so getting another np203 is kinda hard. If anyone knows any other solutions please let me know.

Old np203:

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New np203:

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[kleedus]

I know on a 205 the input gear can be changed

but the 400 case has a larger bearing so the hole needs to be enlarged on a turbo 350 case for the larger bearing

I assume the 203 is the same way but not positive

tear down both 203's and put the good parts in the 400 case

 

[MadOgre]

how about a 205, 208 or even a 241 ? you would have to get the adapter and cross member to go with the case but heh wouldn't that be an upgrade ?

 

[Johhny]

I would love a np205, unfortunately there aren't any around here (Thanks Wrangler owners ), so sticking with the np203 seems like the best option. I build in a Mile Marker convert kit (#501) so at least it functions like a 205 (4x2). If anyone has any question about the 501 kit let me know, it's a really easy convert.

I started working on the swap today but ran into a problem:

I disassembled the old np203:

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took out the input drive gear (32 spline):

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and placed it in the new tcase:

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Everything fits perfectly but I can't seem to reassemble the range box case...

There's a lever with shaft combined with a lockout shift that's located in the range box case itself:

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The lever with shaft goes on 1, the lockout shift goes on 2:

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I have no idea how to connected this when putting the case on, anyone has any suggestions?