I believe they both have the F18 gearbox, the number is stamped on the 'box casing. The gear ratios may differ slightly (e.g. the CDX has slightly higher gearing for better cruising and mpg, whereas the SRI has lower gearing for a more sporty response) but not enough to matter.
Make sure they both have the same type of clutch actuator, as early ones were cable and later ones hydraulic.
The Vectra sites I'm a member of dont have a 'how to' for gearbox removal but there's probably one out there.
It might be easier to buy a Haynes manual.
Probably worth fitting a new clutch at the same time.
spenny, May 2009
