87 rankin 23' with 4.3 omc. don't know where dip stick mounts to motor. Have assemble tube and dip stick assemble. couldn't believe i bought boat and no way to check the oil.
That vintage of OMC would be easy to remove the dip tube and stick without a trace. Look at the oil pan where the drain plug would normally be, that is where the dip tube screws into a unique brass fitting, you may need to look for a donor for parts, somebody probably just plugged off item #57.