It depends on the original engine and the year of the truck. Not all five speeds were compatible.
These are the three that seem to be compatible:

Years Engine Power Torque VIN code
1986–1993 2.8 L 60° V6, TBI 125 hp (93 kW) 150 ft·lbf (203 N·m) R
1988–1995 4.3 L GM 262inch 4300cc V6, TBI 150–165 hp (112–123 kW) 230–235 ft·lbf (312–319 N·m) Z
1990–1993 2.5 L Iron Duke I4, TBI 105 hp (78 kW) 135 ft·lbf (183 N·m) A