How to model a 4 SPEED GEAR BOX in AUTOCAD

I need a 4 speed gearbox deisgn using autocad software.

1 Answer

3D Engineering and Designing for Dummies

just kidding...but it is all about two thinks.
01. master your 3d modeling program
02. master the art of engineering the required item.

beware that it takes years to become a qualified automotive engineer,
so there is not an easy answer on your question.