How do I install dash and rear speakers in a 1994 Buick Regal Custom?

I bought a set of dash and rear speakers and then had a installation diagram sent to me.. it said it was for a 1994 Buick Regal Custom but when I removed the grill for the dash speakers the diagram did not match what was actually there... Does anyone know how to do this properly or a good diagram to show how to do this?|||Does the vehicle have a BOSE system? Is that where the confusion occurs with the wiring? Are you seeing four wires instead of two coming off of the harness?