GM Full-Size Trucks 1970-1979 Repair Guide

Transmission Assembly

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REMOVAL & INSTALLATION



It would be best to drain the transmission before starting. It may be necessary to disconnect and remove the exhaust crossover pipe on V8s, and to disconnect the catalytic converter and remove its support bracket, on models so equipped.

2-Wheel Drive
  1. Disconnect the battery ground cable. Disconnect the detent cable at the carburetor.
  2.  
  3. Raise and support the truck on jackstands.
  4.  
  5. Remove the driveshaft, after matchmarking its flanges.
  6.  
  7. Disconnect the speedometer cable, downshift cable, vacuum modulator line, shift linkage, throttle linkage and fluid cooler lines at the transmission. Remove the filler tube.
  8.  
  9. Support the transmission and unbolt the rear mount from the crossmember. Remove the crossmember.
  10.  
  11. Remove the torque converter underpan, matchmark the flywheel and converter, and remove the converter bolts.
  12.  
  13. Support the engine and lower the transmission slightly for access to the upper transmission to engine bolts.
  14.  
  15. Remove the transmission to engine bolts and pull the transmission back. Rig up a strap or keep the front of the transmission up so the converter doesn't fall out.
  16.  
  17. Reverse the procedure for installation. Bolt the transmission to the engine first, tighten to 34 ft. lbs. (46 Nm), then the converter to the flywheel, tighten to 50 ft. lbs. (68 Nm). Make sure that the converter attaching lugs are flush and that the converter can turn freely before installing the bolts. Tighten the bolts finger-tight, then torque to specification, to insure proper converter alignment.
  18.  

Lubricate the internal yoke splines at the transmission end of the driveshaft with lithium base grease. The grease should seep out through the vent hole.

4-Wheel Drive
1970-72 VEHICLES
  1. Disconnect the battery ground cable. Disconnect the detent cable at the carburetor.
  2.  
  3. Raise and support the truck.
  4.  
  5. Remove the driveshafts, after matchmarking their flanges.
  6.  
  7. Remove the transfer case shift lever.
  8.  
  9. Disconnect the speedometer cable, downshift cable, vacuum modulator line, shift linkage, throttle linkage and fluid cooler lines at the transmission. Remove the filler tube.
  10.  
  11. Support the transmission and transfer case separately. Remove the transmission to adapter case bolts. Unbolt the transfer case from the frame bracket and remove it.
  12.  
  13. Proceed with Steps 5 through 9 of the two wheel drive procedure. See Transfer Case removal and installation for adapter bolt tightening specifications.
  14.  

1973-79 VEHICLES
  1. Disconnect the battery ground cable and remove the transmission dipstick. Detach the downshift cable at the carburetor. Remove the transfer case shift lever knob and boot.
  2.  
  3. Raise and support the truck on jackstands.
  4.  
  5. Remove the skid plate, if any. Remove the flywheel cover.
  6.  
  7. Matchmark the flywheel and torque converter, remove the bolts, and secure the converter so it doesn't fall out of the transmission.
  8.  
  9. Detach the shift linkage, speedometer cable, vacuum modulator line, downshift cable, throttle linkage and cooler times at the transmission. Remove the filler tube.
  10.  
  11. Remove the exhaust crossover pipe to manifold bolts.
  12.  
  13. Unbolt the transfer case adapter from the crossmember. Support the transmission and transfer case. Remove the crossmember.
  14.  
  15. Move the exhaust system aside. Detach the driveshafts after matchmarking their flanges. Disconnect the parking brake cable.
  16.  
  17. Unbolt the transfer case from the frame bracket. Support the engine. Unbolt the transmission from the engine, pull the assembly back, and remove.
  18.  
  19. Reverse the procedure for installation. Bolt the transmission to the engine first, tighten to 34 ft. lbs. (46 Nm), then the converter to the flywheel, tighten to 50 ft. lbs. (68 Nm). Make sure that the converter attaching lugs are flush and that the converter can turn freely before installing the bolts. Tighten the bolts finger tight, then tighten to specification, to insure proper converter alignment.
  20.  

 
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