Johhny
Junior Member
- Joined
- Sep 23, 2014
- Posts
- 5
- Reaction score
- 0
- Location
- South
- First Name
- Johnny
- Truck Year
- 1973
- Truck Model
- Suburban
- Engine Size
- 400ci
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:
New np203:

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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