Last time I had an extended warrenty deal it was offered up as soon as they had the new parts fitted and were ready to return the vehicle. It was written up so that only the new items fitted were covered beyond the scope of the normal warranty. (they also extended the whole thing by 2 months for the time I didnt have the car)
lets say you have a 3 year warranty, you have the car for a year and get a new motor. under the revised warranty if you blow the diff at 3yrs6mnth from date of purchase then thats not covered but if the crank snaps at 3yrs11months then thats covered.
It'd be a great sign if they offer it up straight off the bat for you.

