Removal & Installation - M/t GMC Cab & Chassis V3500

1. Raise and support vehicle on hoist. Drain transfer case. Disconnect speedometer cable. Remove skid plate and crossmember supports. Disconnect drive shafts from transfer case.
2. On A/T equipped models, remove engine strut rod. Disconnect shift lever rod from shift rail link. Support transfer case and remove transfer case-to-transmission adapter bolts. Move transfer case to rear until input shaft clears adapter. Remove assembly from vehicle.

To install, reverse removal procedure. Tighten bolts to specification. See appropriate TORQUE SPECIFICATIONS table.

1. Place transfer case shift lever in "4H" position. Disconnect negative battery cable. Raise vehicle and remove skid plate. Drain transfer case. Mark front and rear output shaft yokes and drive shafts for reassembly reference and remove shafts.
2. Disconnect speedometer cable and vacuum harness from transfer case. Remove shift lever from case. Remove catalytic converter hanger bolts at converter. Remove transmission mount-to-crossmember bolts. Raise transmission and transfer case assembly. Remove transmission mount bolts. Remove mount.
3. Lower complete assembly. Support transfer case and remove transmission-to-transfer case bolts. On A/T equipped models, remove shift lever bracket from transfer case adapter to gain access for upper left attaching bolt. Remove transfer case from transmission.

To install, reverse removal procedure. Always use a new gasket between the transfer case and adapter. Tighten bolts to specification. See appropriate TORQUE SPECIFICATIONS table.

1. Place transfer case in "4H". Raise vehicle. Drain lubricant from transfer case. Remove cotter pin from shift lever swivel. Mark transfer case front and rear output shaft yokes and drive shafts for assembly alignment reference and remove shafts.
2. Disconnect speedometer cable, indicator switch wires and speed sensor wire (if equipped). Disconnect parking brake cable guide from pivot located on right frame rail. On A/T equipped models, remove engine strut rod from transfer case (if equipped).
3. Remove skid plate. Place support under transfer case and remove transfer case-to-transmission adapter bolts. Move transfer case assembly rearward until free of transmission output shaft and remove assembly. Remove all gasket material from rear of transmission adapter housing.

To install, reverse removal procedure. Install new gasket. Tighten bolts to specification. See appropriate TORQUE SPECIFICATIONS table.

1. On models with 117 MM 4-speed transmission, remove shift lever boot retainer bolts. Slide boot assembly upward on shift lever and remove lever. To remove shift lever, push down on collar and turn counterclockwise.
2. On all models, raise and support vehicle under frame. Drain fluid from transmission and transfer case (if equipped). Disconnect speedometer cable at transmission.
3. Remove shift controls from transmission (if not previously removed). Remove parking brake lever, controls, and back-up switch wire as needed. Disconnect drive shaft at transmission.
4. Remove transfer case (if equipped). See «TRANSFER CASE»(/gmc/cab-chassis-v3500/1987-1991/remont/manual-trans/#removal-installation-mt) . Disconnect exhaust pipes from exhaust manifolds as needed. Remove frame crossmember and flywheel inspection plate.
5. On 117 MM 4-speed, remove top 2 transmission-to-clutch housing bolts and install guide pins. Guide pins will support transmission and prevent damage to clutch disc.
6. On all models, remove all transmission-to-clutch housing attaching bolts. Slide transmission rearward until input shaft is clear of clutch hub. Remove assembly from vehicle and remove guide pins if used.

Note. Support clutch release bearing and support assembly when removing transmission main drive gear from flywheel housing. This will prevent release bearing from falling out of flywheel housing.

1. Check that plugs located in rear of bellhousing below transmission mounting bolt holes are tight and not damaged. Note location before removal. Install new plugs if plugs are damaged.
2. Apply a light coat of high-temperature grease to main drive gear splines. Place transmission in high gear. Reverse removal procedures to complete installation. Tighten bolts to specification. See «TORQUE SPECIFICATIONS (EXCEPT "M" & "S/T" SERIES)»(/gmc/cab-chassis-v3500/1987-1991/remont/manual-trans/#removal-installation-mt) .

1. Disconnect negative battery cable. Drain transmission. Remove strut rods (if equipped). Raise vehicle and support. Disconnect shift linkage from transmission.
2. Mark drive shaft for reassembly reference and remove drive shaft. Disconnect speedometer cable and wiring harness. Disconnect exhaust pipe from manifold.
3. Support transmission and remove brace retaining bolts. Note location of spacers. Remove crossmember. Remove transmission retaining bolts. Support clutch release bearing and remove transmission.

1. Apply a light coat of high-temperature grease to main drive gear splines. Reverse removal procedures to complete installation.
2. Braces must be installed with long holes at the transmission end. Tighten braces at clutch housing first then at transmission. Tighten bolts to specification. See «TORQUE SPECIFICATIONS ("M" SERIES)»(/gmc/cab-chassis-v3500/1987-1991/remont/manual-trans/#removal-installation-mt) .

1. Disconnect negative battery cable. Remove shift lever boot screws and slide boot upward on shift lever. Shift transmission into neutral and remove shift lever bolts at transmission. Remove shift lever.
2. Raise vehicle and mark drive shaft for reassembly reference. Remove drive shaft. Disconnect parking brake lever and controls.
3. Remove transfer case (if equipped). See «TRANSFER CASE»(/gmc/cab-chassis-v3500/1987-1991/remont/manual-trans/#removal-installation-mt) . Disconnect exhaust pipe at manifold. Disconnect speedometer cable and electrical connector at transmission.
4. Remove slave cylinder from transmission. Support transmission and remove catalytic converter hanger and support braces. Remove necessary crossmembers.
5. Remove body mounting bolts on left side of body and loosen radiator support bolt. Raise cab on left side as needed to gain access for transmission retaining bolts.
6. Support cab with wood block between frame and cab. Remove transmission-to-engine bolts on all models. Remove transmission.

Apply a light coat of high-temperature grease to main drive gear splines. Place transmission in high gear. Reverse removal procedures to complete installation. Tighten bolts to specification. See TORQUE SPECIFICATIONS ("S/T" SERIES) .

ALL EXCEPT "M" & "S/T" SERIES

TORQUE SPECIFICATIONS (EXCEPT "M" & "S/T" SERIES)

"M" SERIES

TORQUE SPECIFICATIONS ("M" SERIES)

"S/T" SERIES

TORQUE SPECIFICATIONS ("S/T" SERIES)

See also:
• TORQUE SPECIFICATIONS