Shift actuator assembly for operatively engaging and disengaging an associated gear set, said shift actuator assembly comprising: a non-rotatable shift shaft that is axially movable in rectilinear fashion between first and second positions, said shift shaft including a pair of retaining surfaces disposed in space relationship with respect to each other on said shift shaft; a shift fork assembly operatively mounted on said shift shaft and movable between said first and second positions, said shift fork assembly including a housing and a shift fork connected to said housing for operatively engaging and disengaging the associated gear set, a biasing mechanism being disposed on said shift shaft in said housing and between said pair of retaining surfaces, said biasing mechanism being compressed between said retaining surfaces when said shift shaft is disposed in either of its first or second positions; characterized in that said housing defines a retaining mechanism including a pair of cam surfaces disposed on opposite sides of said retaining mechanism, a holding pawl being biased into engagement with said retaining mechanism, said holding pawl including a pair of holding surfaces for releasably engaging said pair of cam surfaces on said retaining mechanism; the shift actuator assembly further comprising a solenoid assembly that releasably engages said holding pawl when said shift shaft is disposed in its first and second positions such that once said solenoid assembly disengages said holding pawl, said cam surfaces on said retaining mechanism cooperate with said holding surfaces on said holding pawl to drive said holding pawl out of engagement with said retaining mechanism thereby releasing the biasing force of said biasing mechanism to drive said housing and said shift fork axially on said shift shaft between engaged and disengaged positions with respect to the associated gear set. a non-rotatable shift shaft that is axially movable in rectilinear fashion between first and second positions, said shift shaft including a pair of retaining surfaces disposed in space relationship with respect to each other on said shift shaft; a shift fork assembly operatively mounted on said shift shaft and movable between said first and second positions, said shift fork assembly including a housing and a shift fork connected to said housing for operatively engaging and disengaging the associated gear set, a biasing mechanism being disposed on said shift shaft in said housing and between said pair of retaining surfaces, said biasing mechanism being compressed between said retaining surfaces when said shift shaft is disposed in either of its first or second positions; said housing defines a retaining mechanism including a pair of cam surfaces disposed on opposite sides of said retaining mechanism, a holding pawl being biased into engagement with said retaining mechanism, said holding pawl including a pair of holding surfaces for releasably engaging said pair of cam surfaces on said retaining mechanism; the shift actuator assembly further comprising a solenoid assembly that releasably engages said holding pawl when said shift shaft is disposed in its first and second positions such that once said solenoid assembly disengages said holding pawl, said cam surfaces on said retaining mechanism cooperate with said holding surfaces on said holding pawl to drive said holding pawl out of engagement with said retaining mechanism thereby releasing the biasing force of said biasing mechanism to drive said housing and said shift fork axially on said shift shaft between engaged and disengaged positions with respect to the associated gear set.