do i need a specific wiring adapter to connect my jvc kd-g343 head unit to the vectra's original wiring?

the lead that i have for the stereo looks like this one.

http://cgi.ebay.co.uk/ISO-STEREO-ADA...item3a570d2b20

but when i remove my original head unit (cd2005) there are 2 small blue plugs and 1 larger blue plug above,does this sound right