Vacuum Modulator Rod: Spectrum
WARNING: This page is about a different car, the 1989 Geo Spectrum, 1988 Chevrolet Spectrum, 1987 Chevrolet Spectrum, and 1986 Chevrolet Spectrum. However, it is still accessible from the selected car via links, so may be relevant.
To determine correct vacuum modulator rod length, measure distance "N" at transaxle. See VACUUM DIAPHRAGM ROD SELECTION for correct rod length to use. Also, see Fig 1.