🔧 Squarebody Chevy Transfer Case Guide (1973–1987)


From farm fields to fire roads, Squarebody Chevy and GMC 4x4s earned their legendary status off-road thanks in part to their rugged transfer cases. Whether you’re running a full-time NP203, a bulletproof NP205, or the versatile NP208, understanding what’s under your rig is essential for upgrades, maintenance, and swaps.

In this guide, we break down every factory transfer case that came in 4WD Squarebody trucks from 1973 to 1987. You'll learn what models were offered, what years they were available, the pros and cons of each, and how to identify them by sight and tag. Let’s dig into what really puts the “4” in your 4x4.


⚙️ Transfer Case Reference Chart (1973–1987)

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Factory Transfer Cases for Chevy/GMC Squarebody Trucks

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  Model         Type             Operation      Years Used               Notes             

|---------|-------------|-----------------|-------------|------------------------------|

  NP203     Full-time      Chain Drive       1973–1979     Full-time 4WD system     

  NP205     Part-time      Gear Drive        1973–1987     Legendary strength       

  NP208     Part-time      Chain Drive       1981–1987     Lightweight, aluminum case   

  NP241C   Part-time      Chain Drive        1987*             Began showing up in late '87 

RW T221    Part-time      Gear Drive        Up to 1973     Found in some early K-series 


*Note: NP241C mostly seen in 1987 R/V Series trucks with fuel injection.


📊 Transfer Case Breakdown: Pros, Cons & Common Issues

🔧 NP203

  • Type: Full-time 4WD, chain drive
  • Pros:
  • Smooth operation
  • Excellent in slick, snowy, or icy conditions
  • High and low range included
  • Cons:
  • Complex differential setup
  • Fuel economy suffers due to full-time 4WD
  • Heavy and bulky
  • Common Issues:
  • Worn chain stretch
  • Center differential issues
  • Conversion kits often installed to make it part-time


🔧 NP205

  • Type: Part-time 4WD, gear drive
  • Pros:
  • Extremely strong and reliable
  • Fully gear-driven (no chain)
  • Commonly used in heavy-duty and military applications
  • Cons:
  • Noisy shifting
  • Heavier than chain-drive options
  • Less forgiving in icy road conditions (no center diff)
  • Common Issues:
  • Input shaft wear
  • Fluid leaks if not properly sealed
  • Linkage adjustment can be finicky


🔧 NP208

  • Type: Part-time 4WD, chain drive
  • Pros:
  • Lightweight aluminum case
  • Smoother operation than NP205
  • More efficient, less rotating mass
  • Cons:
  • Not as durable under heavy loads
  • Chain can stretch or break over time
  • Common Issues:
  • Slipping chain
  • Cracked case if over-torqued
  • Weak tailshaft housing


🔧 NP241C

  • Type: Part-time 4WD, chain drive
  • Pros:
  • Stronger than NP208
  • Smoother operation and better lubrication
  • Common upgrade path from NP208
  • Cons:
  • Only came in late '87 V-series models
  • Can require adapter changes in older frames
  • Common Issues:
  • Shift fork wear
  • Rear housing cracks (if overextended)


🔧 Rockwell T221

  • Type: Part-time 4WD, gear drive
  • Pros:
  • Durable and simple
  • Strong gear setup
  • Cons:
  • Obsolete for most modern builds
  • Very limited parts availability
  • Common Issues:
  • Gear lash, input seal leaks
  • Worn synchronizers if abused


🔍 Transfer Case Identification Tips

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How to Identify Your T-Case

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1. Case Material:

  - NP203: Cast iron, bulky, heavy

  - NP205: Cast iron, squared off, gear-driven

  - NP208: Aluminum, smooth curves

  - NP241C: Aluminum, ribbed case


2. Tag Location:

  - Look for a metal tag riveted to the rear of the case or adapter

  - Tag lists model number and build date


3. Shift Pattern (on shifter or bezel):

  - NP203: HI - LOC - N - LO - LOC

  - NP205: 4HI - N - 4LO (some with 2HI detent)

  - NP208: 2HI - 4HI - N - 4LO

  - NP241: Same as NP208, but slightly smoother engagement


4. Front Output:

  - NP203: Large round output with differential housing

  - NP205: Heavy-duty yoke style with fixed yokes

  - NP208/241: Slip-yoke or flange, lighter setup


🛠️ Which Transfer Case Is Right for You?

Use:                                                                 Best Transfer Case:

Heavy towing / durability                                    NP205

Snow/ice road conditions                                   NP203 (or NP241)

Weight savings / MPG                                         NP208 / NP241C

Daily driving + off-road                                          NP208 or NP241C

Rock crawling builds                                             NP205 (or doubled)

Factory restoration                                                Match to year/model


🔚 Closing Statement

Transfer cases are the heart of your Squarebody’s 4x4 system. Whether you’ve got a lightweight NP208 or a brute-force NP205, knowing what’s under your truck helps you plan for the trails ahead — and avoid surprises in the shop.

This guide covered every factory option from 1973 to 1987, helping you identify, understand, and decide whether to keep, rebuild, or upgrade your transfer case.

For more drivetrain tech, real-world part reviews, and Squarebody know-how, stick with Blazin’ Biddles Off-Road — where old iron meets new ideas.