I know that some chevy engines will bolt right up not sure but if you want a motor thats got torque which you want while wheeling look an see if the 4.3 vortec or 4.6 vortec will bolt up. The 4.6 vortec is one of the more dependable motors chevy made i've had three of them an I never had any problems with them drove the crap of them an nothing ever broke on me

 

Mazda MPV makes an 3.0L v6 5spd. Although they are SUPER hard to find, they do make them. 1989 to 1998 they were 100% Mazda